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WHENtheobjectsofaninquiry，inanydepartment，haveprinciples，conditions，orelements，itisthroughacquaintancewiththesethatknowledge，thatistosayscientificknowledge，isattained。Forwedonotthinkthatweknowathinguntilweareacquaintedwithitsprimaryconditionsorfirstprinciples，andhavecarriedouranalysisasfarasitssimplestelements。PlainlythereforeinthescienceofNature，asinotherbranchesofstudy，ourfirsttaskwillbetotrytodeterminewhatrelatestoitsprinciples。
Thenaturalwayofdoingthisistostartfromthethingswhicharemoreknowableandobvioustousandproceedtowardsthosewhichareclearerandmoreknowablebynature；forthesamethingsarenot\'knowablerelativelytous\'and\'knowable\'withoutqualification。Sointhepresentinquirywemustfollowthismethodandadvancefromwhatismoreobscurebynature，butclearertous，towardswhatismoreclearandmoreknowablebynature。
Nowwhatistousplainandobviousatfirstisratherconfusedmasses，theelementsandprinciplesofwhichbecomeknowntouslaterbyanalysis。Thuswemustadvancefromgeneralitiestoparticulars；foritisawholethatisbestknowntosense-perception，andageneralityisakindofwhole，comprehendingmanythingswithinit，likeparts。Muchthesamethinghappensintherelationofthenametotheformula。Aname，e。g。\'round\'，meansvaguelyasortofwhole:itsdefinitionanalysesthisintoitsparticularsenses。
Similarlyachildbeginsbycallingallmen\'father\'，andallwomen\'mother\'，butlaterondistinguisheseachofthem。
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Theprinciplesinquestionmustbeeitheraoneorbmorethanone。Ifaone，itmustbeeitherimotionless，asParmenidesandMelissusassert，oriiinmotion，asthephysicistshold，somedeclaringairtobethefirstprinciple，otherswater。Ifbmorethanone，theneitheriafiniteoriianinfiniteplurality。Ififinitebutmorethanone，theneithertwoorthreeorfourorsomeothernumber。Ifiiinfinite，theneitherasDemocritusbelievedoneinkind，butdifferinginshapeorform；ordifferentinkindandevencontrary。
Asimilarinquiryismadebythosewhoinquireintothenumberofexistents:fortheyinquirewhethertheultimateconstituentsofexistingthingsareoneormany，andifmany，whetherafiniteoraninfiniteplurality。Sotheytooareinquiringwhethertheprincipleorelementisoneormany。
NowtoinvestigatewhetherBeingisoneandmotionlessisnotacontributiontothescienceofNature。Forjustasthegeometerhasnothingmoretosaytoonewhodeniestheprinciplesofhisscience-thisbeingaquestionforadifferentscienceorfororcommontoall-soamaninvestigatingprinciplescannotarguewithonewhodeniestheirexistence。ForifBeingisjustone，andoneinthewaymentioned，thereisaprinciplenolonger，sinceaprinciplemustbetheprincipleofsomethingorthings。
ToinquirethereforewhetherBeingisoneinthissensewouldbelikearguingagainstanyotherpositionmaintainedforthesakeofargumentsuchastheHeracliteanthesis，orsuchathesisasthatBeingisonemanorlikerefutingamerelycontentiousargument-adescriptionwhichappliestotheargumentsbothofMelissusandofParmenides:theirpremissesarefalseandtheirconclusionsdonotfollow。OrrathertheargumentofMelissusisgrossandpalpableandoffersnodifficultyatall:acceptoneridiculouspropositionandtherestfollows-asimpleenoughproceeding。
Wephysicists，ontheotherhand，musttakeforgrantedthatthethingsthatexistbynatureare，eitherallorsomeofthem，inmotionwhichisindeedmadeplainbyinduction。Moreover，nomanofscienceisboundtosolveeverykindofdifficultythatmayberaised，butonlyasmanyasaredrawnfalselyfromtheprinciplesofthescience:itisnotourbusinesstorefutethosethatdonotariseinthisway:justasitisthedutyofthegeometertorefutethesquaringofthecirclebymeansofsegments，butitisnothisdutytorefuteAntiphon\'sproof。Atthesametimetheholdersofthetheoryofwhichwearespeakingdoincidentallyraisephysicalquestions，thoughNatureisnottheirsubject:soitwillperhapsbeaswelltospendafewwordsonthem，especiallyastheinquiryisnotwithoutscientificinterest。
Themostpertinentquestionwithwhichtobeginwillbethis:Inwhatsenseisitassertedthatallthingsareone?For\'is\'isusedinmanysenses。Dotheymeanthatallthings\'are\'substanceorquantitiesorqualities?And，further，areallthingsonesubstance-oneman，onehorse，oronesoul-orqualityandthatoneandthesame-whiteorhotorsomethingofthekind?Theseareallverydifferentdoctrinesandallimpossibletomaintain。
Forifbothsubstanceandquantityandqualityare，then，whethertheseexistindependentlyofeachotherornot，Beingwillbemany。
Ifontheotherhanditisassertedthatallthingsarequalityorquantity，then，whethersubstanceexistsornot，anabsurdityresults，iftheimpossiblecanproperlybecalledabsurd。Fornoneoftheotherscanexistindependently:substancealoneisindependent:foreverythingispredicatedofsubstanceassubject。NowMelissussaysthatBeingisinfinite。Itisthenaquantity。Fortheinfiniteisinthecategoryofquantity，whereassubstanceorqualityoraffectioncannotbeinfiniteexceptthroughaconcomitantattribute，thatis，ifatthesametimetheyarealsoquantities。Fortodefinetheinfiniteyoumustusequantityinyourformula，butnotsubstanceorquality。IfthenBeingisbothsubstanceandquantity，itistwo，notone:ifonlysubstance，itisnotinfiniteandhasnomagnitude；
fortohavethatitwillhavetobeaquantity。
Again，\'one\'itself，nolessthan\'being\'，isusedinmanysenses，sowemustconsiderinwhatsensethewordisusedwhenitissaidthattheAllisone。
Nowwesaythatathecontinuousisoneorthatbtheindivisibleisone，orcthingsaresaidtobe\'one\'，whentheiressenceisoneandthesame，as\'liquor\'and\'drink\'。
IfatheirOneisoneinthesenseofcontinuous，itismany，forthecontinuousisdivisibleadinfinitum。
Thereis，indeed，adifficultyaboutpartandwhole，perhapsnotrelevanttothepresentargument，yetdeservingconsiderationonitsownaccount-namely，whetherthepartandthewholeareoneormorethanone，andhowtheycanbeoneormany，and，iftheyaremorethanone，inwhatsensetheyaremorethanone。Similarlywiththepartsofwholeswhicharenotcontinuous。Further，ifeachofthetwopartsisindivisiblyonewiththewhole，thedifficultyarisesthattheywillbeindivisiblyonewitheachotheralso。
Buttoproceed:IfbtheirOneisoneasindivisible，nothingwillhavequantityorquality，andsotheonewillnotbeinfinite，asMelissussays-nor，indeed，limited，asParmenidessays，forthoughthelimitisindivisible，thelimitedisnot。
Butifcallthingsareoneinthesenseofhavingthesamedefinition，like\'raiment\'and\'dress\'，thenitturnsoutthattheyaremaintainingtheHeracliteandoctrine，foritwillbethesamething\'tobegood\'and\'tobebad\'，and\'tobegood\'and\'tobenotgood\'，andsothesamethingwillbe\'good\'and\'notgood\'，andmanandhorse；infact，theirviewwillbe，notthatallthingsareone，butthattheyarenothing；andthat\'tobeofsuch-and-suchaquality\'
isthesameas\'tobeofsuch-and-suchasize\'。
Eventhemorerecentoftheancientthinkerswereinapotherlestthesamethingshouldturnoutintheirhandsbothoneandmany。Sosome，likeLycophron，wereledtoomit\'is\'，otherstochangethemodeofexpressionandsay\'themanhasbeenwhitened\'insteadof\'iswhite\'，and\'walks\'insteadof\'iswalking\'，forfearthatiftheyaddedtheword\'is\'theyshouldbemakingtheonetobemany-asif\'one\'and\'being\'werealwaysusedinoneandthesamesense。What\'is\'maybemanyeitherindefinitionforexample\'tobewhite\'isonething，\'tobemusical\'another，yetthesamethingbeboth，sotheoneismanyorbydivision，asthewholeanditsparts。Onthispoint，indeed，theywerealreadygettingintodifficultiesandadmittedthattheonewasmany-asiftherewasanydifficultyaboutthesamethingbeingbothoneandmany，providedthatthesearenotopposites；for\'one\'maymeaneither\'potentiallyone\'or\'actuallyone\'。
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If，then，weapproachthethesisinthiswayitseemsimpossibleforallthingstobeone。Further，theargumentstheyusetoprovetheirpositionarenotdifficulttoexpose。Forbothofthemreasoncontentiously-ImeanbothMelissusandParmenides。[Theirpremissesarefalseandtheirconclusionsdonotfollow。OrrathertheargumentofMelissusisgrossandpalpableandoffersnodifficultyatall:admitoneridiculouspropositionandtherestfollows-asimpleenoughproceeding。]ThefallacyofMelissusisobvious。Forhesupposesthattheassumption\'whathascomeintobeingalwayshasabeginning\'justifiestheassumption\'whathasnotcomeintobeinghasnobeginning\'。Thenthisalsoisabsurd，thatineverycasethereshouldbeabeginningofthething-notofthetimeandnotonlyinthecaseofcomingtobeinthefullsensebutalsointhecaseofcomingtohaveaquality-asifchangenevertookplacesuddenly。Again，doesitfollowthatBeing，ifone，ismotionless?Whyshoulditnotmove，thewholeofitwithinitself，aspartsofitdowhichareunities，e。g。thiswater?Again，whyisqualitativechangeimpossible?But，further，Beingcannotbeoneinform，thoughitmaybeinwhatitismadeof。Evensomeofthephysicistsholdittobeoneinthelatterway，thoughnotintheformer。Manobviouslydiffersfromhorseinform，andcontrariesfromeachother。
ThesamekindofargumentholdsgoodagainstParmenidesalso，besidesanythatmayapplyspeciallytohisview:theanswertohimbeingthat\'thisisnottrue\'and\'thatdoesnotfollow\'。Hisassumptionthatoneisusedinasinglesenseonlyisfalse，becauseitisusedinseveral。Hisconclusiondoesnotfollow，becauseifwetakeonlywhitethings，andif\'white\'hasasinglemeaning，nonethelesswhatiswhitewillbemanyandnotone。Forwhatiswhitewillnotbeoneeitherinthesensethatitiscontinuousorinthesensethatitmustbedefinedinonlyoneway。\'Whiteness\'willbedifferentfrom\'whathaswhiteness\'。Nordoesthismeanthatthereisanythingthatcanexistseparately，overandabovewhatiswhite。
For\'whiteness\'and\'thatwhichiswhite\'differindefinition，notinthesensethattheyarethingswhichcanexistapartfromeachother。ButParmenideshadnotcomeinsightofthisdistinction。
Itisnecessaryforhim，then，toassumenotonlythat\'being\'hasthesamemeaning，ofwhateveritispredicated，butfurtherthatitmeans1whatjustisand2whatisjustone。
Itmustbeso，for1anattributeispredicatedofsomesubject，sothatthesubjecttowhich\'being\'isattributedwillnotbe，asitissomethingdifferentfrom\'being\'。Something，therefore，whichisnotwillbe。Hence\'substance\'willnotbeapredicateofanythingelse。Forthesubjectcannotbeabeing，unless\'being\'meansseveralthings，insuchawaythateachissomething。Butexhypothesi\'being\'meansonlyonething。
If，then，\'substance\'isnotattributedtoanything，butotherthingsareattributedtoit，howdoes\'substance\'meanwhatisratherthanwhatisnot?Forsupposethat\'substance\'isalso\'white\'。
Sincethedefinitionofthelatterisdifferentforbeingcannotevenbeattributedtowhite，asnothingiswhichisnot\'substance\'，itfollowsthat\'white\'isnot-being——andthatnotinthesenseofaparticularnot-being，butinthesensethatitisnotatall。Hence\'substance\'isnot；foritistruetosaythatitiswhite，whichwefoundtomeannot-being。Iftoavoidthiswesaythateven\'white\'
meanssubstance，itfollowsthat\'being\'hasmorethanonemeaning。
Inparticular，then，Beingwillnothavemagnitude，ifitissubstance。Foreachofthetwopartsmustheinadifferentsense。
2Substanceisplainlydivisibleintoothersubstances，ifweconsiderthemerenatureofadefinition。Forinstance，if\'man\'isasubstance，\'animal\'and\'biped\'mustalsobesubstances。Forifnotsubstances，theymustbeattributes-andifattributes，attributeseitherofamanorofbsomeothersubject。Butneitherispossible。
aAnattributeiseitherthatwhichmayormaynotbelongtothesubjectorthatinwhosedefinitionthesubjectofwhichitisanattributeisinvolved。Thus\'sitting\'isanexampleofaseparableattribute，while\'snubness\'containsthedefinitionof\'nose\'，towhichweattributesnubness。Further，thedefinitionofthewholeisnotcontainedinthedefinitionsofthecontentsorelementsofthedefinitoryformula；thatof\'man\'forinstancein\'biped\'，orthatof\'whiteman\'in\'white\'。Ifthenthisisso，andif\'biped\'issupposedtobeanattributeof\'man\'，itmustbeeitherseparable，sothat\'man\'mightpossiblynotbe\'biped\'，orthedefinitionof\'man\'mustcomeintothedefinitionof\'biped\'-whichisimpossible，astheconverseisthecase。
bIf，ontheotherhand，wesupposethat\'biped\'and\'animal\'
areattributesnotofmanbutofsomethingelse，andarenoteachofthemasubstance，then\'man\'toowillbeanattributeofsomethingelse。Butwemustassumethatsubstanceisnottheattributeofanything，thatthesubjectofwhichboth\'biped\'and\'animal\'andeachseparatelyarepredicatedisthesubjectalsoofthecomplex\'bipedanimal\'。
ArewethentosaythattheAlliscomposedofindivisiblesubstances?Somethinkersdid，inpointoffact，givewaytobotharguments。Totheargumentthatallthingsareoneifbeingmeansonething，theyconcededthatnot-beingis；tothatfrombisection，theyyieldedbypositingatomicmagnitudes。Butobviouslyitisnottruethatifbeingmeansonething，andcannotatthesametimemeanthecontradictoryofthis，therewillbenothingwhichisnot，forevenifwhatisnotcannotbewithoutqualification，thereisnoreasonwhyitshouldnotbeaparticularnot-being。Tosaythatallthingswillbeone，ifthereisnothingbesidesBeingitself，isabsurd。Forwhounderstands\'beingitself\'tobeanythingbutaparticularsubstance?Butifthisisso，thereisnothingtopreventtherebeingmanybeings，ashasbeensaid。
Itis，then，clearlyimpossibleforBeingtobeoneinthissense。
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Thephysicistsontheotherhandhavetwomodesofexplanation。
Thefirstsetmaketheunderlyingbodyoneeitheroneofthethreeorsomethingelsewhichisdenserthanfireandrarerthanairthengenerateeverythingelsefromthis，andobtainmultiplicitybycondensationandrarefaction。Nowthesearecontraries，whichmaybegeneralizedinto\'excessanddefect\'。ComparePlato\'s\'GreatandSmall\'-exceptthathemakethesehismatter，theonehisform，whiletheotherstreattheonewhichunderliesasmatterandthecontrariesasdifferentiae，i。e。forms。
Thesecondsetassertthatthecontrarietiesarecontainedintheoneandemergefromitbysegregation，forexampleAnaximanderandalsoallthosewhoassertthat\'whatis\'isoneandmany，likeEmpedoclesandAnaxagoras；fortheytooproduceotherthingsfromtheirmixturebysegregation。Thesediffer，however，fromeachotherinthattheformerimaginesacycleofsuchchanges，thelatterasingleseries。Anaxagorasagainmadebothhis\'homceomerous\'
substancesandhiscontrariesinfiniteinmultitude，whereasEmpedoclespositsonlytheso-calledelements。
ThetheoryofAnaxagorasthattheprinciplesareinfiniteinmultitudewasprobablyduetohisacceptanceofthecommonopinionofthephysiciststhatnothingcomesintobeingfromnot-being。Forthisisthereasonwhytheyusethephrase\'allthingsweretogether\'andthecomingintobeingofsuchandsuchakindofthingisreducedtochangeofquality，whilesomespokeofcombinationandseparation。Moreover，thefactthatthecontrariesproceedfromeachotherledthemtotheconclusion。Theone，theyreasoned，musthavealreadyexistedintheother；forsinceeverythingthatcomesintobeingmustariseeitherfromwhatisorfromwhatisnot，anditisimpossibleforittoarisefromwhatisnotonthispointallthephysicistsagree，theythoughtthatthetruthofthealternativenecessarilyfollowed，namelythatthingscomeintobeingoutofexistentthings，i。e。outofthingsalreadypresent，butimperceptibletooursensesbecauseofthesmallnessoftheirbulk。Sotheyassertthateverythinghasbeenmixedinevery。thing，becausetheysaweverythingarisingoutofeverything。Butthings，astheysay，appeardifferentfromoneanotherandreceivedifferentnamesaccordingtothenatureoftheparticleswhicharenumericallypredominantamongtheinnumerableconstituentsofthemixture。Fornothing，theysay，ispurelyandentirelywhiteorblackorsweet，boneorflesh，butthenatureofathingisheldtobethatofwhichitcontainsthemost。
Now1theinfinitequainfiniteisunknowable，sothatwhatisinfiniteinmultitudeorsizeisunknowableinquantity，andwhatisinfiniteinvarietyofkindisunknowableinquality。Buttheprinciplesinquestionareinfinitebothinmultitudeandinkind。
Thereforeitisimpossibletoknowthingswhicharecomposedofthem；foritiswhenweknowthenatureandquantityofitscomponentsthatwesupposeweknowacomplex。
Further2ifthepartsofawholemaybeofanysizeinthedirectioneitherofgreatnessorofsmallnessby\'parts\'Imeancomponentsintowhichawholecanbedividedandwhichareactuallypresentinit，itisnecessarythatthewholethingitselfmaybeofanysize。Clearly，therefore，sinceitisimpossibleforananimalorplanttobeindefinitelybigorsmall，neithercanitspartsbesuch，orthewholewillbethesame。Butflesh，bone，andthelikearethepartsofanimals，andthefruitsarethepartsofplants。
Henceitisobviousthatneitherflesh，bone，noranysuchthingcanbeofindefinitesizeinthedirectioneitherofthegreateroroftheless。
Again3accordingtothetheoryallsuchthingsarealreadypresentinoneanotheranddonotcomeintobeingbutareconstituentswhichareseparatedout，andathingreceivesitsdesignationfromitschiefconstituent。Further，anythingmaycomeoutofanything-waterbysegregationfromfleshandfleshfromwater。Hence，sinceeveryfinitebodyisexhaustedbytherepeatedabstractionofafinitebody，itseemsobviouslytofollowthateverythingcannotsubsistineverythingelse。Forletfleshbeextractedfromwaterandagainmorefleshbeproducedfromtheremainderbyrepeatingtheprocessofseparation:
then，eventhoughthequantityseparatedoutwillcontinuallydecrease，stillitwillnotfallbelowacertainmagnitude。If，therefore，theprocesscomestoanend，everythingwillnotbeineverythingelsefortherewillbenofleshintheremainingwater；
ifontheotherhanditdoesnot，andfurtherextractionisalwayspossible，therewillbeaninfinitemultitudeoffiniteequalparticlesinafinitequantity-whichisimpossible。Anotherproofmaybeadded:Sinceeverybodymustdiminishinsizewhensomethingistakenfromit，andfleshisquantitativelydefiniteinrespectbothofgreatnessandsmallness，itisclearthatfromtheminimumquantityoffleshnobodycanbeseparatedout；forthefleshleftwouldbelessthantheminimumofflesh。
Lastly4ineachofhisinfinitebodiestherewouldbealreadypresentinfinitefleshandbloodandbrain-havingadistinctexistence，however，fromoneanother，andnolessrealthantheinfinitebodies，andeachinfinite:whichiscontrarytoreason。
Thestatementthatcompleteseparationneverwilltakeplaceiscorrectenough，thoughAnaxagorasisnotfullyawareofwhatitmeans。
Foraffectionsareindeedinseparable。Ifthencoloursandstateshadenteredintothemixture，andifseparationtookplace，therewouldbea\'white\'ora\'healthy\'whichwasnothingbutwhiteorhealthy，i。e。wasnotthepredicateofasubject。Sohis\'Mind\'isanabsurdpersonaimingattheimpossible，ifheissupposedtowishtoseparatethem，anditisimpossibletodoso，bothinrespectofquantityandofquality-ofquantity，becausethereisnominimummagnitude，andofquality，becauseaffectionsareinseparable。
NorisAnaxagorasrightaboutthecomingtobeofhomogeneousbodies。Itistruethereisasenseinwhichclayisdividedintopiecesofclay，butthereisanotherinwhichitisnot。Waterandairare，andaregenerated\'from\'eachother，butnotinthewayinwhichbrickscome\'from\'ahouseandagainahouse\'from\'bricks；
anditisbettertoassumeasmallerandfinitenumberofprinciples，asEmpedoclesdoes。
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Allthinkersthenagreeinmakingthecontrariesprinciples，boththosewhodescribetheAllasoneandunmovedforevenParmenidestreatshotandcoldasprinciplesunderthenamesoffireandearth
andthosetoowhousetherareandthedense。ThesameistrueofDemocritusalso，withhisplenumandvoid，bothofwhichexist，besays，theoneasbeing，theotherasnot-being。Againhespeaksofdifferencesinposition，shape，andorder，andthesearegeneraofwhichthespeciesarecontraries，namely，ofposition，aboveandbelow，beforeandbehind；ofshape，angularandangle-less，straightandround。
Itisplainthenthattheyallinonewayoranotheridentifythecontrarieswiththeprinciples。Andwithgoodreason。Forfirstprinciplesmustnotbederivedfromoneanothernorfromanythingelse，whileeverythinghastobederivedfromthem。Buttheseconditionsarefulfilledbytheprimarycontraries，whicharenotderivedfromanythingelsebecausetheyareprimary，norfromeachotherbecausetheyarecontraries。
Butwemustseehowthiscanbearrivedatasareasonedresult，aswellasinthewayjustindicated。
Ourfirstpresuppositionmustbethatinnaturenothingactson，orisactedonby，anyotherthingatrandom，normayanythingcomefromanythingelse，unlesswemeanthatitdoessoinvirtueofaconcomitantattribute。Forhowcould\'white\'comefrom\'musical\'，unless\'musical\'happenedtobeanattributeofthenot-whiteoroftheblack?No，\'white\'comesfrom\'not-white\'-andnotfromany\'not-white\'，butfromblackorsomeintermediatecolour。Similarly，\'musical\'comestobefrom\'not-musical\'，butnotfromanythingotherthanmusical，butfrom\'unmusical\'oranyintermediatestatetheremaybe。
Noragaindothingspassintothefirstchancething；\'white\'doesnotpassinto\'musical\'except，itmaybe，invirtueofaconcomitantattribute，butinto\'not-white\'-andnotintoanychancethingwhichisnotwhite，butintoblackoranintermediatecolour；\'musical\'
passesinto\'not-musical\'-andnotintoanychancethingotherthanmusical，butinto\'unmusical\'oranyintermediatestatetheremaybe。
Thesameholdsofotherthingsalso:eventhingswhicharenotsimplebutcomplexfollowthesameprinciple，buttheoppositestatehasnotreceivedaname，sowefailtonoticethefact。Whatisintunemustcomefromwhatisnotintune，andviceversa；thetunedpassesintountunedness-andnotintoanyuntunedness，butintothecorrespondingopposite。Itdoesnotmatterwhetherwetakeattunement，order，orcompositionforourillustration；theprincipleisobviouslythesameinall，andinfactappliesequallytotheproductionofahouse，astatue，oranyothercomplex。Ahousecomesfromcertainthingsinacertainstateofseparationinsteadofconjunction，astatueoranyotherthingthathasbeenshapedfromshapelessness-eachoftheseobjectsbeingpartlyorderandpartlycomposition。
Ifthenthisistrue，everythingthatcomestobeorpassesawayfrom，orpassesinto，itscontraryoranintermediatestate。Buttheintermediatesarederivedfromthecontraries-colours，forinstance，fromblackandwhite。Everything，therefore，thatcomestobebyanaturalprocessiseitheracontraryoraproductofcontraries。
Uptothispointwehavepracticallyhadmostoftheotherwritersonthesubjectwithus，asIhavesaidalready:forallofthemidentifytheirelements，andwhattheycalltheirprinciples，withthecontraries，givingnoreasonindeedforthetheory，butcontrainedasitwerebythetruthitself。Theydiffer，however，fromoneanotherinthatsomeassumecontrarieswhicharemoreprimary，otherscontrarieswhicharelessso:somethosemoreknowableintheorderofexplanation，othersthosemorefamiliartosense。Forsomemakehotandcold，oragainmoistanddry，theconditionsofbecoming；whileothersmakeoddandeven，oragainLoveandStrife；andthesedifferfromeachotherinthewaymentioned。
Hencetheirprinciplesareinonesensethesame，inanotherdifferent；differentcertainly，asindeedmostpeoplethink，butthesameinasmuchastheyareanalogous；forallaretakenfromthesametableofcolumns，someofthepairsbeingwider，othersnarrowerinextent。Inthiswaythentheirtheoriesareboththesameanddifferent，somebetter，someworse；some，asIhavesaid，takeastheircontrarieswhatismoreknowableintheorderofexplanation，otherswhatismorefamiliartosense。Theuniversalismoreknowableintheorderofexplanation，theparticularintheorderofsense:forexplanationhastodowiththeuniversal，sensewiththeparticular。\'Thegreatandthesmall\'，forexample，belongtotheformerclass，\'thedenseandtherare\'tothelatter。
Itisclearthenthatourprinciplesmustbecontraries。
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Thenextquestioniswhethertheprinciplesaretwoorthreeormoreinnumber。
Onetheycannotbe，fortherecannotbeonecontrary。Norcantheybeinnumerable，because，ifso，Beingwillnotbeknowable:andinanyonegenusthereisonlyonecontrariety，andsubstanceisonegenus:
alsoafinitenumberissufficient，andafinitenumber，suchastheprinciplesofEmpedocles，isbetterthananinfinitemultitude；forEmpedoclesprofessestoobtainfromhisprinciplesallthatAnaxagorasobtainsfromhisinnumerableprinciples。Lastly，somecontrariesaremoreprimarythanothers，andsomearisefromothers-forexamplesweetandbitter，whiteandblack-whereastheprinciplesmustalwaysremainprinciples。
Thiswillsufficetoshowthattheprinciplesareneitheronenorinnumerable。
Granted，then，thattheyarealimitednumber，itisplausibletosupposethemmorethantwo。Foritisdifficulttoseehoweitherdensityshouldbeofsuchanatureastoactinanywayonrarityorrarityondensity。Thesameistrueofanyotherpairofcontraries；
forLovedoesnotgatherStrifetogetherandmakethingsoutofit，nordoesStrifemakeanythingoutofLove，butbothactonathirdthingdifferentfromboth。Someindeedassumemorethanonesuchthingfromwhichtheyconstructtheworldofnature。
Otherobjectionstotheviewthatitisnotnecessarytoassumeathirdprincipleasasubstratummaybeadded。1Wedonotfindthatthecontrariesconstitutethesubstanceofanything。Butwhatisafirstprincipleoughtnottobethepredicateofanysubject。Ifitwere，therewouldbeaprincipleofthesupposedprinciple:forthesubjectisaprinciple，andpriorpresumablytowhatispredicatedofit。Again2weholdthatasubstanceisnotcontrarytoanothersubstance。Howthencansubstancebederivedfromwhatarenotsubstances?Orhowcannon-substancesbepriortosubstance?
Ifthenweacceptboththeformerargumentandthisone，wemust，topreserveboth，assumeathirdsomewhatasthesubstratumofthecontraries，suchasisspokenofbythosewhodescribetheAllasonenature-waterorfireorwhatisintermediatebetweenthem。Whatisintermediateseemspreferable；forfire，earth，air，andwaterarealreadyinvolvedwithpairsofcontraries。Thereis，therefore，muchtobesaidforthosewhomaketheunderlyingsubstancedifferentfromthesefour；oftherest，thenextbestchoiceisair，aspresentingsensibledifferencesinalessdegreethantheothers；
andafterair，water。All，however，agreeinthis，thattheydifferentiatetheirOnebymeansofthecontraries，suchasdensityandrarityandmoreandless，whichmayofcoursebegeneralized，ashasalreadybeensaidintoexcessanddefect。IndeedthisdoctrinetoothattheOneandexcessanddefectaretheprinciplesofthings
wouldappeartobeofoldstanding，thoughindifferentforms；fortheearlythinkersmadethetwotheactiveandtheonethepassiveprinciple，whereassomeofthemorerecentmaintainthereverse。
Tosupposethenthattheelementsarethreeinnumberwouldseem，fromtheseandsimilarconsiderations，aplausibleview，asIsaidbefore。Ontheotherhand，theviewthattheyaremorethanthreeinnumberwouldseemtobeuntenable。
Fortheonesubstratumissufficienttobeactedon；butifwehavefourcontraries，therewillbetwocontrarieties，andweshallhavetosupposeanintermediatenatureforeachpairseparately。If，ontheotherhand，thecontrarieties，beingtwo，cangeneratefromeachother，thesecondcontrarietywillbesuperfluous。Moreover，itisimpossiblethatthereshouldbemorethanoneprimarycontrariety。Forsubstanceisasinglegenusofbeing，sothattheprinciplescandifferonlyaspriorandposterior，notingenus；inasinglegenusthereisalwaysasinglecontrariety，alltheothercontrarietiesinitbeingheldtobereducibletoone。
Itisclearthenthatthenumberofelementsisneitheronenormorethantwoorthree；butwhethertwoorthreeis，asIsaid，aquestionofconsiderabledifficulty。
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Wewillnowgiveourownaccount，approachingthequestionfirstwithreferencetobecominginitswidestsense:forweshallbefollowingthenaturalorderofinquiryifwespeakfirstofcommoncharacteristics，andtheninvestigatethecharacteristicsofspecialcases。
Wesaythatonethingcomestobefromanotherthing，andonesortofthingfromanothersortofthing，bothinthecaseofsimpleandofcomplexthings。Imeanthefollowing。Wecansay1\'manbecomesmusical\'，2whatis\'not-musicalbecomesmusical\'，or3，the\'not-musicalmanbecomesamusicalman\'。Nowwhatbecomesin1and2-\'man\'and\'notmusical\'-Icallsimple，andwhateachbecomes-\'musical\'-simplealso。Butwhen3wesaythe\'not-musicalmanbecomesamusicalman\'，bothwhatbecomesandwhatitbecomesarecomplex。
Asregardsoneofthesesimple\'thingsthatbecome\'wesaynotonly\'thisbecomesso-and-so\'，butalso\'frombeingthis，comestobeso-and-so\'，as\'frombeingnot-musicalcomestobemusical\'；asregardstheotherwedonotsaythisinallcases，aswedonotsay1\'frombeingamanhecametobemusical\'butonly\'themanbecamemusical\'。
Whena\'simple\'thingissaidtobecomesomething，inonecase1
itsurvivesthroughtheprocess，intheother2itdoesnot。Formanremainsamanandissuchevenwhenhebecomesmusical，whereaswhatisnotmusicalorisunmusicaldoesnotcontinuetoexist，eithersimplyorcombinedwiththesubject。
Thesedistinctionsdrawn，onecangatherfromsurveyingthevariouscasesofbecominginthewaywearedescribingthat，aswesay，theremustalwaysbeanunderlyingsomething，namelythatwhichbecomes，andthatthis，thoughalwaysonenumerically，informatleastisnotone。BythatImeanthatitcanbedescribedindifferentways。For\'tobeman\'isnotthesameas\'tobeunmusical\'。
Onepartsurvives，theotherdoesnot:whatisnotanoppositesurvivesfor\'man\'survives，but\'not-musical\'or\'unmusical\'doesnotsurvive，nordoesthecompoundofthetwo，namely\'unmusicalman\'。
Wespeakof\'becomingthatfromthis\'insteadof\'thisbecomingthat\'moreinthecaseofwhatdoesnotsurvivethechange-\'becomingmusicalfromunmusical\'，not\'fromman\'-butthereareexceptions，aswesometimesusethelatterformofexpressionevenofwhatsurvives；wespeakof\'astatuecomingtobefrombronze\'，notofthe\'bronzebecomingastatue\'。Thechange，however，fromanoppositewhichdoesnotsurviveisdescribedindifferentlyinbothways，\'becomingthatfromthis\'or\'thisbecomingthat\'。Wesayboththat\'theunmusicalbecomesmusical\'，andthat\'fromunmusicalhebecomesmusical\'。Andsobothformsareusedofthecomplex，\'becomingamusicalmanfromanunmusicalman\'，andunmusicalmanbecomingamusicalman\'。
Buttherearedifferentsensesof\'comingtobe\'。Insomecaseswedonotusetheexpression\'cometobe\'，but\'cometobeso-and-so\'。
Onlysubstancesaresaidto\'cometobe\'intheunqualifiedsense。
Nowinallcasesotherthansubstanceitisplainthattheremustbesomesubject，namely，thatwhichbecomes。Forweknowthatwhenathingcomestobeofsuchaquantityorqualityorinsucharelation，time，orplace，asubjectisalwayspresupposed，sincesubstancealoneisnotpredicatedofanothersubject，buteverythingelseofsubstance。
Butthatsubstancestoo，andanythingelsethatcanbesaid\'tobe\'withoutqualification，cometobefromsomesubstratum，willappearonexamination。Forwefindineverycasesomethingthatunderliesfromwhichproceedsthatwhichcomestobe；forinstance，animalsandplantsfromseed。
Generallythingswhichcometobe，cometobeindifferentways:1
bychangeofshape，asastatue；2byaddition，asthingswhichgrow；3bytakingaway，astheHermesfromthestone；4byputtingtogether，asahouse；5byalteration，asthingswhich\'turn\'inrespectoftheirmaterialsubstance。
Itisplainthattheseareallcasesofcomingtobefromasubstratum。
Thus，clearly，fromwhathasbeensaid，whatevercomestobeisalwayscomplex。Thereis，ontheonehand，asomethingwhichcomesintoexistence，andagainbsomethingwhichbecomesthat-thelatterbintwosenses，eitherthesubjectortheopposite。Bythe\'opposite\'Imeanthe\'unmusical\'，bythe\'subject\'\'man\'，andsimilarlyIcalltheabsenceofshapeorformororderthe\'opposite\'，andthebronzeorstoneorgoldthe\'subject\'。
Plainlythen，ifthereareconditionsandprincipleswhichconstitutenaturalobjectsandfromwhichtheyprimarilyareorhavecometobe-havecometobe，Imean，whateachissaidtobeinitsessentialnature，notwhateachisinrespectofaconcomitantattribute-plainly，Isay，everythingcomestobefrombothsubjectandform。For\'musicalman\'iscomposedinawayof\'man\'and\'musical\':
youcananalyseitintothedefinitionsofitselements。Itisclearthenthatwhatcomestobewillcometobefromtheseelements。
Nowthesubjectisonenumerically，thoughitistwoinform。Foritistheman，thegold-the\'matter\'generally-thatiscounted，foritismoreofthenatureofa\'this\'，andwhatcomestobedoesnotcomefromitinvirtueofaconcomitantattribute；theprivation，ontheotherhand，andthecontraryareincidentalintheprocess。Andthepositiveformisone-theorder，theacquiredartofmusic，oranysimilarpredicate。
Thereisasense，therefore，inwhichwemustdeclaretheprinciplestobetwo，andasenseinwhichtheyarethree；asenseinwhichthecontrariesaretheprinciples-sayforexamplethemusicalandtheunmusical，thehotandthecold，thetunedandtheuntuned-andasenseinwhichtheyarenot，sinceitisimpossibleforthecontrariestobeactedonbyeachother。Butthisdifficultyalsoissolvedbythefactthatthesubstratumisdifferentfromthecontraries，foritisitselfnotacontrary。Theprinciplesthereforeare，inaway，notmoreinnumberthanthecontraries，butasitweretwo，noryetpreciselytwo，sincethereisadifferenceofessentialnature，butthree。For\'tobeman\'isdifferentfrom\'tobeunmusical\'，and\'tobeunformed\'from\'tobebronze\'。
Wehavenowstatedthenumberoftheprinciplesofnaturalobjectswhicharesubjecttogeneration，andhowthenumberisreached:anditisclearthattheremustbeasubstratumforthecontraries，andthatthecontrariesmustbetwo。Yetinanotherwayofputtingitthisisnotnecessary，asoneofthecontrarieswillservetoeffectthechangebyitssuccessiveabsenceandpresence。
Theunderlyingnatureisanobjectofscientificknowledge，byananalogy。Forasthebronzeistothestatue，thewoodtothebed，orthematterandtheformlessbeforereceivingformtoanythingwhichhasform，soistheunderlyingnaturetosubstance，i。e。the\'this\'orexistent。
Thisthenisoneprinciplethoughnotoneorexistentinthesamesenseasthe\'this\'，andthedefinitionwasoneasweagreed；thenfurtherthereisitscontrary，theprivation。Inwhatsensethesearetwo，andinwhatsensemore，hasbeenstatedabove。Briefly，weexplainedfirstthatonlythecontrarieswereprinciples，andlaterthatasubstratumwasindispensable，andthattheprincipleswerethree；ourlaststatementhaselucidatedthedifferencebetweenthecontraries，themutualrelationoftheprinciples，andthenatureofthesubstratum。Whethertheformorthesubstratumistheessentialnatureofaphysicalobjectisnotyetclear。Butthattheprinciplesarethree，andinwhatsense，andthewayinwhicheachisaprinciple，isclear。
Somuchthenforthequestionofthenumberandthenatureoftheprinciples。
8
Wewillnowproceedtoshowthatthedifficultyoftheearlythinkers，aswellasourown，issolvedinthiswayalone。
Thefirstofthosewhostudiedscienceweremisledintheirsearchfortruthandthenatureofthingsbytheirinexperience，whichasitwerethrustthemintoanotherpath。Sotheysaythatnoneofthethingsthatareeithercomestobeorpassesoutofexistence，becausewhatcomestobemustdosoeitherfromwhatisorfromwhatisnot，bothofwhichareimpossible。Forwhatiscannotcometobebecauseitisalready，andfromwhatisnotnothingcouldhavecometobebecausesomethingmustbepresentasasubstratum。Sotootheyexaggeratedtheconsequenceofthis，andwentsofarastodenyeventheexistenceofapluralityofthings，maintainingthatonlyBeingitselfis。Suchthenwastheiropinion，andsuchthereasonforitsadoption。
Ourexplanationontheotherhandisthatthephrases\'somethingcomestobefromwhatisorfromwhatisnot\'，\'whatisnotorwhatisdoessomethingorhassomethingdonetoitorbecomessomeparticularthing\'，aretobetakeninthefirstwayofputtingourexplanationinthesamesenseas\'adoctordoessomethingorhassomethingdonetohim\'，\'isorbecomessomethingfrombeingadoctor。\'
Theseexpressionsmaybetakenintwosenses，andsotoo，clearly，may\'frombeing\'，and\'beingactsorisactedon\'。Adoctorbuildsahouse，notquadoctor，butquahousebuilder，andturnsgray，notquadoctor，butquadark-haired。Ontheotherhandhedoctorsorfailstodoctorquadoctor。Butweareusingwordsmostappropriatelywhenwesaythatadoctordoessomethingorundergoessomething，orbecomessomethingfrombeingadoctor，ifhedoes，undergoes，orbecomesquadoctor。Clearlythenalso\'tocometobeso-and-sofromnot-being\'
means\'quanot-being\'。
Itwasthroughfailuretomakethisdistinctionthatthosethinkersgavethematterup，andthroughthiserrorthattheywentsomuchfartherastrayastosupposethatnothingelsecomestobeorexistsapartfromBeingitself，thusdoingawaywithallbecoming。
Weourselvesareinagreementwiththeminholdingthatnothingcanbesaidwithoutqualificationtocomefromwhatisnot。Butneverthelesswemaintainthatathingmay\'cometobefromwhatisnot\'-thatis，inaqualifiedsense。Forathingcomestobefromtheprivation，whichinitsownnatureisnot-being，-thisnotsurvivingasaconstituentoftheresult。Yetthiscausessurprise，anditisthoughtimpossiblethatsomethingshouldcometobeinthewaydescribedfromwhatisnot。
Inthesamewaywemaintainthatnothingcomestobefrombeing，andthatbeingdoesnotcometobeexceptinaqualifiedsense。Inthatway，however，itdoes，justasanimalmightcometobefromanimal，andananimalofacertainkindfromananimalofacertainkind。
Thus，supposeadogtocometobefromahorse。Thedogwouldthen，itistrue，cometobefromanimalaswellasfromananimalofacertainkindbutnotasanimal，forthatisalreadythere。Butifanythingistobecomeananimal，notinaqualifiedsense，itwillnotbefromanimal:andifbeing，notfrombeing-norfromnot-beingeither，forithasbeenexplainedthatby\'fromnotbeing\'wemeanfromnot-beingquanot-being。
Notefurtherthatwedonotsubverttheprinciplethateverythingeitherisorisnot。
Thisthenisonewayofsolvingthedifficulty。Anotherconsistsinpointingoutthatthesamethingscanbeexplainedintermsofpotentialityandactuality。Butthishasbeendonewithgreaterprecisionelsewhere。So，aswesaid，thedifficultieswhichconstrainpeopletodenytheexistenceofsomeofthethingswementionedarenowsolved。Foritwasthisreasonwhichalsocausedsomeoftheearlierthinkerstoturnsofarasidefromtheroadwhichleadstocomingtobeandpassingawayandchangegenerally。
Iftheyhadcomeinsightofthisnature，alltheirignorancewouldhavebeendispelled。
9
Others，indeed，haveapprehendedthenatureinquestion，butnotadequately。
Inthefirstplacetheyallowthatathingmaycometobewithoutqualificationfromnotbeing，acceptingonthispointthestatementofParmenides。Secondly，theythinkthatifthesubstratumisonenumerically，itmusthavealsoonlyasinglepotentiality-whichisaverydifferentthing。
Nowwedistinguishmatterandprivation，andholdthatoneofthese，namelythematter，isnot-beingonlyinvirtueofanattributewhichithas，whiletheprivationinitsownnatureisnot-being；andthatthematterisnearly，inasenseis，substance，whiletheprivationinnosenseis。They，ontheotherhand，identifytheirGreatandSmallalikewithnotbeing，andthatwhethertheyaretakentogetherasoneorseparately。Theirtriadisthereforeofquiteadifferentkindfromours。Fortheygotsofarastoseethattheremustbesomeunderlyingnature，buttheymakeitone-forevenifonephilosophermakesadyadofit，whichhecallsGreatandSmall，theeffectisthesame，forheoverlookedtheothernature。Fortheonewhichpersistsisajointcause，withtheform，ofwhatcomestobe-amother，asitwere。Butthenegativepartofthecontrarietymayoftenseem，ifyouconcentrateyourattentiononitasanevilagent，nottoexistatall。
Foradmittingwiththemthatthereissomethingdivine，good，anddesirable，weholdthattherearetwootherprinciples，theonecontrarytoit，theothersuchasofitsownnaturetodesireandyearnforit。Buttheconsequenceoftheirviewisthatthecontrarydesiresitswtextinction。Yettheformcannotdesireitself，foritisnotdefective；norcanthecontrarydesireit，forcontrariesaremutuallydestructive。Thetruthisthatwhatdesirestheformismatter，asthefemaledesiresthemaleandtheuglythebeautiful-onlytheuglyorthefemalenotpersebutperaccidens。
Themattercomestobeandceasestobeinonesense，whileinanotheritdoesnot。Asthatwhichcontainstheprivation，itceasestobeinitsownnature，forwhatceasestobe-theprivation-iscontainedwithinit。Butaspotentialityitdoesnotceasetobeinitsownnature，butisnecessarilyoutsidethesphereofbecomingandceasingtobe。Forifitcametobe，somethingmusthaveexistedasaprimarysubstratumfromwhichitshouldcomeandwhichshouldpersistinit；butthisisitsownspecialnature，sothatitwillbebeforecomingtobe。Formydefinitionofmatterisjustthis-theprimarysubstratumofeachthing，fromwhichitcomestobewithoutqualification，andwhichpersistsintheresult。Andifitceasestobeitwillpassintothatatthelast，soitwillhaveceasedtobebeforeceasingtobe。
Theaccuratedeterminationofthefirstprincipleinrespectofform，whetheritisoneormanyandwhatitisorwhattheyare，istheprovinceoftheprimarytypeofscience；sothesequestionsmaystandovertillthen。Butofthenatural，i。e。perishable，formsweshallspeakintheexpositionswhichfollow。
Theabove，then，maybetakenassufficienttoestablishthatthereareprinciplesandwhattheyareandhowmanythereare。Nowletusmakeafreshstartandproceed。
BookII
1
Ofthingsthatexist，someexistbynature，somefromothercauses。
\'Bynature\'theanimalsandtheirpartsexist，andtheplantsandthesimplebodiesearth，fire，air，water-forwesaythattheseandthelikeexist\'bynature\'。
Allthethingsmentionedpresentafeatureinwhichtheydifferfromthingswhicharenotconstitutedbynature。Eachofthemhaswithinitselfaprincipleofmotionandofstationarinessinrespectofplace，orofgrowthanddecrease，orbywayofalteration。Ontheotherhand，abedandacoatandanythingelseofthatsort，quareceivingthesedesignationsi。e。insofarastheyareproductsofart-havenoinnateimpulsetochange。Butinsofarastheyhappentobecomposedofstoneorofearthorofamixtureofthetwo，theydohavesuchanimpulse，andjusttothatextentwhichseemstoindicatethatnatureisasourceorcauseofbeingmovedandofbeingatrestinthattowhichitbelongsprimarily，invirtueofitselfandnotinvirtueofaconcomitantattribute。
Isay\'notinvirtueofaconcomitantattribute\'，becauseforinstanceamanwhoisadoctormightcurehimself。Neverthelessitisnotinsofarasheisapatientthathepossessestheartofmedicine:itmerelyhashappenedthatthesamemanisdoctorandpatient-andthatiswhytheseattributesarenotalwaysfoundtogether。Soitiswithallotherartificialproducts。Noneofthemhasinitselfthesourceofitsownproduction。Butwhileinsomecasesforinstancehousesandtheotherproductsofmanuallabour
thatprincipleisinsomethingelseexternaltothething，inothersthosewhichmaycauseachangeinthemselvesinvirtueofaconcomitantattribute-itliesinthethingsthemselvesbutnotinvirtueofwhattheyare。
\'Nature\'theniswhathasbeenstated。Things\'haveanature\'whichhaveaprincipleofthiskind。Eachofthemisasubstance；foritisasubject，andnaturealwaysimpliesasubjectinwhichitinheres。
Theterm\'accordingtonature\'isappliedtoallthesethingsandalsototheattributeswhichbelongtotheminvirtueofwhattheyare，forinstancethepropertyoffiretobecarriedupwards-whichisnota\'nature\'nor\'hasanature\'butis\'bynature\'or\'accordingtonature\'。
Whatnatureis，then，andthemeaningoftheterms\'bynature\'and\'accordingtonature\'，hasbeenstated。Thatnatureexists，itwouldbeabsurdtotrytoprove；foritisobviousthattherearemanythingsofthiskind，andtoprovewhatisobviousbywhatisnotisthemarkofamanwhoisunabletodistinguishwhatisself-evidentfromwhatisnot。Thisstateofmindisclearlypossible。Amanblindfrombirthmightreasonaboutcolours。Presumablythereforesuchpersonsmustbetalkingaboutwordswithoutanythoughttocorrespond。
Someidentifythenatureorsubstanceofanaturalobjectwiththatimmediateconstituentofitwhichtakenbyitselfiswithoutarrangement，e。g。thewoodisthe\'nature\'ofthebed，andthebronzethe\'nature\'ofthestatue。
AsanindicationofthisAntiphonpointsoutthatifyouplantedabedandtherottingwoodacquiredthepowerofsendingupashoot，itwouldnotbeabedthatwouldcomeup，butwood-whichshowsthatthearrangementinaccordancewiththerulesoftheartismerelyanincidentalattribute，whereastherealnatureistheother，which，further，persistscontinuouslythroughtheprocessofmaking。
Butifthematerialofeachoftheseobjectshasitselfthesamerelationtosomethingelse，saybronzeorgoldtowater，bonesorwoodtoearthandsoon，thattheysaywouldbetheirnatureandessence。Consequentlysomeassertearth，othersfireorairorwaterorsomeorallofthese，tobethenatureofthethingsthatare。
Forwhateveranyoneofthemsupposedtohavethischaracter-whetheronethingormorethanonething-thisorthesehedeclaredtobethewholeofsubstance，allelsebeingitsaffections，states，ordispositions。Everysuchthingtheyheldtobeeternalforitcouldnotpassintoanythingelse，butotherthingstocomeintobeingandceasetobetimeswithoutnumber。
Thisthenisoneaccountof\'nature\'，namelythatitistheimmediatematerialsubstratumofthingswhichhaveinthemselvesaprincipleofmotionorchange。
Anotheraccountisthat\'nature\'istheshapeorformwhichisspecifiedinthedefinitionofthething。
Fortheword\'nature\'isappliedtowhatisaccordingtonatureandthenaturalinthesamewayas\'art\'isappliedtowhatisartisticoraworkofart。Weshouldnotsayinthelattercasethatthereisanythingartisticaboutathing，ifitisabedonlypotentially，notyethavingtheformofabed；norshouldwecallitaworkofart。Thesameistrueofnaturalcompounds。Whatispotentiallyfleshorbonehasnotyetitsown\'nature\'，anddoesnotexistuntilitreceivestheformspecifiedinthedefinition，whichwenameindefiningwhatfleshorboneis。Thusinthesecondsenseof\'nature\'itwouldbetheshapeorformnotseparableexceptinstatementofthingswhichhaveinthemselvesasourceofmotion。Thecombinationofthetwo，e。g。man，isnot\'nature\'but\'bynature\'or\'natural\'。
Theformindeedis\'nature\'ratherthanthematter；forathingismoreproperlysaidtobewhatitiswhenithasattainedtofulfilmentthanwhenitexistspotentially。Againmanisbornfromman，butnotbedfrombed。Thatiswhypeoplesaythatthefigureisnotthenatureofabed，butthewoodis-ifthebedsproutednotabedbutwoodwouldcomeup。Butevenifthefigureisart，thenonthesameprincipletheshapeofmanishisnature。Formanisbornfromman。
Wealsospeakofathing\'snatureasbeingexhibitedintheprocessofgrowthbywhichitsnatureisattained。The\'nature\'inthissenseisnotlike\'doctoring\'，whichleadsnottotheartofdoctoringbuttohealth。Doctoringmuststartfromtheart，notleadtoit。Butitisnotinthiswaythatnatureintheonesenseisrelatedtonatureintheother。Whatgrowsquagrowinggrowsfromsomethingintosomething。Intowhatthendoesitgrow?Notintothatfromwhichitarosebutintothattowhichittends。Theshapethenisnature。
\'Shape\'and\'nature\'，itshouldbeadded，areintwosenses。Fortheprivationtooisinawayform。Butwhetherinunqualifiedcomingtobethereisprivation，i。e。acontrarytowhatcomestobe，wemustconsiderlater。
2
Wehavedistinguished，then，thedifferentwaysinwhichtheterm\'nature\'isused。
Thenextpointtoconsiderishowthemathematiciandiffersfromthephysicist。Obviouslyphysicalbodiescontainsurfacesandvolumes，linesandpoints，andthesearethesubject-matterofmathematics。
Further，isastronomydifferentfromphysicsoradepartmentofit?Itseemsabsurdthatthephysicistshouldbesupposedtoknowthenatureofsunormoon，butnottoknowanyoftheiressentialattributes，particularlyasthewritersonphysicsobviouslydodiscusstheirshapealsoandwhethertheearthandtheworldaresphericalornot。
Nowthemathematician，thoughhetootreatsofthesethings，neverthelessdoesnottreatofthemasthelimitsofaphysicalbody；nordoesheconsidertheattributesindicatedastheattributesofsuchbodies。Thatiswhyheseparatesthem；forinthoughttheyareseparablefrommotion，anditmakesnodifference，nordoesanyfalsityresult，iftheyareseparated。TheholdersofthetheoryofFormsdothesame，thoughtheyarenotawareofit；fortheyseparatetheobjectsofphysics，whicharelessseparablethanthoseofmathematics。Thisbecomesplainifonetriestostateineachofthetwocasesthedefinitionsofthethingsandoftheirattributes。
\'Odd\'and\'even\'，\'straight\'and\'curved\'，andlikewise\'number\'，\'line\'，and\'figure\'，donotinvolvemotion；notso\'flesh\'and\'bone\'
and\'man\'-thesearedefinedlike\'snubnose\'，notlike\'curved\'。
Similarevidenceissuppliedbythemorephysicalofthebranchesofmathematics，suchasoptics，harmonics，andastronomy。Theseareinawaytheconverseofgeometry。Whilegeometryinvestigatesphysicallinesbutnotquaphysical，opticsinvestigatesmathematicallines，butquaphysical，notquamathematical。
Since\'nature\'hastwosenses，theformandthematter，wemustinvestigateitsobjectsaswewouldtheessenceofsnubness。Thatis，suchthingsareneitherindependentofmatternorcanbedefinedintermsofmatteronly。Heretooindeedonemightraiseadifficulty。
Sincetherearetwonatures，withwhichisthephysicistconcerned?Orshouldheinvestigatethecombinationofthetwo?Butifthecombinationofthetwo，thenalsoeachseverally。Doesitbelongthentothesameortodifferentsciencestoknoweachseverally?
Ifwelookattheancients，physicswouldtobeconcernedwiththematter。ItwasonlyveryslightlythatEmpedoclesandDemocritustouchedontheformsandtheessence。
Butifontheotherhandartimitatesnature，anditisthepartofthesamedisciplinetoknowtheformandthematteruptoapointe。g。thedoctorhasaknowledgeofhealthandalsoofbileandphlegm，inwhichhealthisrealized，andthebuilderbothoftheformofthehouseandofthematter，namelythatitisbricksandbeams，andsoforth:ifthisisso，itwouldbethepartofphysicsalsotoknownatureinbothitssenses。
Again，\'thatforthesakeofwhich\'，ortheend，belongstothesamedepartmentofknowledgeasthemeans。Butthenatureistheendor\'thatforthesakeofwhich\'。Forifathingundergoesacontinuouschangeandthereisastagewhichislast，thisstageistheendor\'thatforthesakeofwhich\'。Thatiswhythepoetwascarriedawayintomakinganabsurdstatementwhenhesaid\'hehastheendforthesakeofwhichhewasborn\'。Fornoteverystagethatislastclaimstobeanend，butonlythatwhichisbest。
Fortheartsmaketheirmaterialsomesimply\'make\'it，othersmakeitserviceable，andweuseeverythingasifitwasthereforoursake。Wealsoareinasenseanend。\'Thatforthesakeofwhich\'hastwosenses:thedistinctionismadeinourworkOnPhilosophy。Thearts，therefore，whichgovernthematterandhaveknowledgearetwo，namelytheartwhichusestheproductandtheartwhichdirectstheproductionofit。Thatiswhytheusingartalsoisinasensedirective；butitdiffersinthatitknowstheform，whereastheartwhichisdirectiveasbeingconcernedwithproductionknowsthematter。Forthehelmsmanknowsandprescribeswhatsortofformahelmshouldhave，theotherfromwhatwooditshouldbemadeandbymeansofwhatoperations。Intheproductsofart，however，wemakethematerialwithaviewtothefunction，whereasintheproductsofnaturethematteristhereallalong。
Again，matterisarelativeterm:toeachformtherecorrespondsaspecialmatter。Howfarthenmustthephysicistknowtheformoressence?Uptoapoint，perhaps，asthedoctormustknowsineworthesmithbronzei。e。untilheunderstandsthepurposeofeach:
andthephysicistisconcernedonlywiththingswhoseformsareseparableindeed，butdonotexistapartfrommatter。Manisbegottenbymanandbythesunaswell。Themodeofexistenceandessenceoftheseparableitisthebusinessoftheprimarytypeofphilosophytodefine。
3
Nowthatwehaveestablishedthesedistinctions，wemustproceedtoconsidercauses，theircharacterandnumber。Knowledgeistheobjectofourinquiry，andmendonotthinktheyknowathingtilltheyhavegraspedthe\'why\'ofwhichistograspitsprimarycause。Soclearlywetoomustdothisasregardsbothcomingtobeandpassingawayandeverykindofphysicalchange，inorderthat，knowingtheirprinciples，wemaytrytorefertotheseprincipleseachofourproblems。
Inonesense，then，1thatoutofwhichathingcomestobeandwhichpersists，iscalled\'cause\'，e。g。thebronzeofthestatue，thesilverofthebowl，andthegeneraofwhichthebronzeandthesilverarespecies。
Inanothersense2theformorthearchetype，i。e。thestatementoftheessence，anditsgenera，arecalled\'causes\'e。g。oftheoctavetherelationof2:1，andgenerallynumber，andthepartsinthedefinition。
Again3theprimarysourceofthechangeorcomingtorest；e。g。
themanwhogaveadviceisacause，thefatheriscauseofthechild，andgenerallywhatmakesofwhatismadeandwhatcauseschangeofwhatischanged。
Again4inthesenseofendor\'thatforthesakeofwhich\'athingisdone，e。g。healthisthecauseofwalkingabout。\'Whyishewalkingabout?\'wesay。\'Tobehealthy\'，and，havingsaidthat，wethinkwehaveassignedthecause。Thesameistruealsoofalltheintermediatestepswhicharebroughtaboutthroughtheactionofsomethingelseasmeanstowardstheend，e。g。reductionofflesh，purging，drugs，orsurgicalinstrumentsaremeanstowardshealth。
Allthesethingsare\'forthesakeof\'theend，thoughtheydifferfromoneanotherinthatsomeareactivities，othersinstruments。
Thisthenperhapsexhauststhenumberofwaysinwhichtheterm\'cause\'isused。
Asthewordhasseveralsenses，itfollowsthatthereareseveralcausesofthesamethingnotmerelyinvirtueofaconcomitantattribute，e。g。boththeartofthesculptorandthebronzearecausesofthestatue。Thesearecausesofthestatuequastatue，notinvirtueofanythingelsethatitmaybe-onlynotinthesameway，theonebeingthematerialcause，theotherthecausewhencethemotioncomes。Somethingscauseeachotherreciprocally，e。g。hardworkcausesfitnessandviceversa，butagainnotinthesameway，buttheoneasend，theotherastheoriginofchange。Furtherthesamethingisthecauseofcontraryresults。Forthatwhichbyitspresencebringsaboutoneresultissometimesblamedforbringingaboutthecontrarybyitsabsence。Thusweascribethewreckofashiptotheabsenceofthepilotwhosepresencewasthecauseofitssafety。
Allthecausesnowmentionedfallintofourfamiliardivisions。
Thelettersarethecausesofsyllables，thematerialofartificialproducts，fire，&c。，ofbodies，thepartsofthewhole，andthepremissesoftheconclusion，inthesenseof\'thatfromwhich\'。Ofthesepairstheonesetarecausesinthesenseofsubstratum，e。g。
theparts，theothersetinthesenseofessence-thewholeandthecombinationandtheform。Buttheseedandthedoctorandtheadviser，andgenerallythemaker，areallsourceswhencethechangeorstationarinessoriginates，whiletheothersarecausesinthesenseoftheendorthegoodoftherest；for\'thatforthesakeofwhich\'
meanswhatisbestandtheendofthethingsthatleaduptoit。
Whetherwesaythe\'gooditselforthe\'apparentgood\'makesnodifference。
Suchthenisthenumberandnatureofthekindsofcause。
Nowthemodesofcausationaremany，thoughwhenbroughtunderheadstheytoocanbereducedinnumber。For\'cause\'isusedinmanysensesandevenwithinthesamekindonemaybepriortoanothere。g。
thedoctorandtheexpertarecausesofhealth，therelation2:1andnumberoftheoctave，andalwayswhatisinclusivetowhatisparticular。Anothermodeofcausationistheincidentalanditsgenera，e。g。inoneway\'Polyclitus\'，inanother\'sculptor\'isthecauseofastatue，because\'beingPolyclitus\'and\'sculptor\'areincidentallyconjoined。Alsotheclassesinwhichtheincidentalattributeisincluded；thus\'aman\'couldbesaidtobethecauseofastatueor，generally，\'alivingcreature\'。Anincidentalattributetoomaybemoreorlessremote，e。g。supposethat\'apaleman\'or\'amusicalman\'weresaidtobethecauseofthestatue。
Allcauses，bothproperandincidental，maybespokenofeitheraspotentialorasactual；e。g。thecauseofahousebeingbuiltiseither\'house-builder\'or\'house-builderbuilding\'。
Similardistinctionscanbemadeinthethingsofwhichthecausesarecauses，e。g。of\'thisstatue\'orof\'statue\'orof\'image\'
generally，of\'thisbronze\'orof\'bronze\'orof\'material\'generally。
Sotoowiththeincidentalattributes。Againwemayuseacomplexexpressionforeitherandsay，e。g。neither\'Polyclitus\'nor\'sculptor\'but\'Polyclitus，sculptor\'。
Allthesevarioususes，however，cometosixinnumber，undereachofwhichagaintheusageistwofold。Causemeanseitherwhatisparticularoragenus，oranincidentalattributeoragenusofthat，andtheseeitherasacomplexoreachbyitself；andallsixeitherasactualoraspotential。Thedifferenceisthismuch，thatcauseswhichareactuallyatworkandparticularexistandceasetoexistsimultaneouslywiththeireffect，e。g。thishealingpersonwiththisbeing-healedpersonandthathouse-buildingmanwiththatbeing-builthouse；butthisisnotalwaystrueofpotentialcauses——thehouseandthehousebuilderdonotpassawaysimultaneously。
Ininvestigatingthecauseofeachthingitisalwaysnecessarytoseekwhatismostpreciseasalsoinotherthings:thusmanbuildsbecauseheisabuilder，andabuilderbuildsinvirtueofhisartofbuilding。Thislastcausethenisprior:andsogenerally。
Further，genericeffectsshouldbeassignedtogenericcauses，particulareffectstoparticularcauses，e。g。statuetosculptor，thisstatuetothissculptor；andpowersarerelativetopossibleeffects，actuallyoperatingcausestothingswhichareactuallybeingeffected。
Thismustsufficeforouraccountofthenumberofcausesandthemodesofcausation。
4
Butchancealsoandspontaneityarereckonedamongcauses:manythingsaresaidbothtobeandtocometobeasaresultofchanceandspontaneity。Wemustinquirethereforeinwhatmannerchanceandspontaneityarepresentamongthecausesenumerated，andwhethertheyarethesameordifferent，andgenerallywhatchanceandspontaneityare。
Somepeopleevenquestionwhethertheyarerealornot。Theysaythatnothinghappensbychance，butthateverythingwhichweascribetochanceorspontaneityhassomedefinitecause，e。g。coming\'bychance\'intothemarketandfindingthereamanwhomonewantedbutdidnotexpecttomeetisduetoone\'swishtogoandbuyinthemarket。Similarlyinothercasesofchanceitisalwayspossible，theymaintain，tofindsomethingwhichisthecause；butnotchance，forifchancewerereal，itwouldseemstrangeindeed，andthequestionmightberaised，whyonearthnoneofthewisemenofoldinspeakingofthecausesofgenerationanddecaytookaccountofchance；whenceitwouldseemthattheytoodidnotbelievethatanythingisbychance。Butthereisafurthercircumstancethatissurprising。Manythingsbothcometobeandarebychanceandspontaneity，andalthoughknowthateachofthemcanbeascribedtosomecauseastheoldargumentsaidwhichdeniedchance，neverthelesstheyspeakofsomeofthesethingsashappeningbychanceandothersnot。Forthisreasonalsotheyoughttohaveatleastreferredtothematterinsomewayorother。
Certainlytheearlyphysicistsfoundnoplaceforchanceamongthecauseswhichtheyrecognized-love，strife，mind，fire，orthelike。
Thisisstrange，whethertheysupposedthatthereisnosuchthingaschanceorwhethertheythoughtthereisbutomittedtomentionit-andthattoowhentheysometimesusedit，asEmpedoclesdoeswhenhesaysthattheairisnotalwaysseparatedintothehighestregion，but\'asitmaychance\'。Atanyratehesaysinhiscosmogonythat\'ithappenedtorunthatwayatthattime，butitoftenranotherwise。\'Hetellsusalsothatmostofthepartsofanimalscametobebychance。
Therearesometoowhoascribethisheavenlysphereandalltheworldstospontaneity。Theysaythatthevortexarosespontaneously，i。e。themotionthatseparatedandarrangedinitspresentorderallthatexists。Thisstatementmightwellcausesurprise。Fortheyareassertingthatchanceisnotresponsiblefortheexistenceorgenerationofanimalsandplants，natureormindorsomethingofthekindbeingthecauseofthemforitisnotanychancethingthatcomesfromagivenseedbutanolivefromonekindandamanfromanother；andyetatthesametimetheyassertthattheheavenlysphereandthedivinestofvisiblethingsarosespontaneously，havingnosuchcauseasisassignedtoanimalsandplants。Yetifthisisso，itisafactwhichdeservestobedweltupon，andsomethingmightwellhavebeensaidaboutit。Forbesidestheotherabsurditiesofthestatement，itisthemoreabsurdthatpeopleshouldmakeitwhentheyseenothingcomingtobespontaneouslyintheheavens，butmuchhappeningbychanceamongthethingswhichastheysayarenotduetochance；whereasweshouldhaveexpectedexactlytheopposite。
Otherstherearewho，indeed，believethatchanceisacause，butthatitisinscrutabletohumanintelligence，asbeingadivinethingandfullofmystery。
Thuswemustinquirewhatchanceandspontaneityare，whethertheyarethesameordifferent，andhowtheyfitintoourdivisionofcauses。