WEareseekingtheprinciplesandthecausesofthethingsthat
are，andobviouslyofthemquabeing。For，whilethereisacauseof
healthandofgoodcondition，andtheobjectsofmathematicshave
firstprinciplesandelementsandcauses，andingeneraleveryscience
whichisratiocinativeoratallinvolvesreasoningdealswith
causesandprinciples，moreorlessprecise，allthesesciencesmark
offsomeparticularbeing-somegenus，andinquireintothis，butnot
intobeingsimplynorquabeing，nordotheyofferanydiscussionof
theessenceofthethingsofwhichtheytreat；butstartingfromthe
essence-somemakingitplaintothesenses，othersassumingitasa
hypothesis-theythendemonstrate，moreorlesscogently，theessential
attributesofthegenuswithwhichtheydeal。Itisobvious，
therefore，thatsuchaninductionyieldsnodemonstrationofsubstance
oroftheessence，butsomeotherwayofexhibitingit。And
similarlythesciencesomitthequestionwhetherthegenuswith
whichtheydealexistsordoesnotexist，becauseitbelongstothe
samekindofthinkingtoshowwhatitisandthatitis。
Andsincenaturalscience，likeothersciences，isinfactabout
oneclassofbeing，i。e。tothatsortofsubstancewhichhasthe
principleofitsmovementandrestpresentinitself，evidentlyit
isneitherpracticalnorproductive。Forinthecaseofthingsmade
theprincipleisinthemaker-itiseitherreasonorartorsome
faculty，whileinthecaseofthingsdoneitisinthedoer-viz。will，
forthatwhichisdoneandthatwhichiswilledarethesame。
Therefore，ifallthoughtiseitherpracticalorproductiveor
theoretical，physicsmustbeatheoreticalscience，butitwill
theorizeaboutsuchbeingasadmitsofbeingmoved，andabout
substance-as-definedforthemostpartonlyasnotseparablefrom
matter。Now，wemustnotfailtonoticethemodeofbeingofthe
essenceandofitsdefinition，for，withoutthis，inquiryisbutidle。
Ofthingsdefined，i。e。of’whats’，somearelike’snub’，andsome
like’concave’。Andthesedifferbecause’snub’isboundupwith
matterforwhatissnubisaconcavenose，whileconcavityis
independentofperceptiblematter。Ifthenallnaturalthingsarea
analogoustothesnubintheirnature；e。g。nose，eye，face，flesh，
bone，and，ingeneral，animal；leaf，root，bark，and，ingeneral，
plantfornoneofthesecanbedefinedwithoutreferenceto
movement-theyalwayshavematter，itisclearhowwemustseekand
definethe’what’inthecaseofnaturalobjects，andalsothatit
belongstothestudentofnaturetostudyevensoulinacertain
sense，i。e。somuchofitasisnotindependentofmatter。
Thatphysics，then，isatheoreticalscience，isplainfrom
theseconsiderations。Mathematicsalso，however，istheoretical；but
whetheritsobjectsareimmovableandseparablefrommatter，isnotat
presentclear；still，itisclearthatsomemathematicaltheorems
considerthemquaimmovableandquaseparablefrommatter。Butif
thereissomethingwhichiseternalandimmovableandseparable，
clearlytheknowledgeofitbelongstoatheoreticalscience，-not，
however，tophysicsforphysicsdealswithcertainmovablethings
nortomathematics，buttoasciencepriortoboth。Forphysics
dealswiththingswhichexistseparatelybutarenotimmovable，and
somepartsofmathematicsdealwiththingswhichareimmovablebut
presumablydonotexistseparately，butasembodiedinmatter；while
thefirstsciencedealswiththingswhichbothexistseparatelyand
areimmovable。Nowallcausesmustbeeternal，butespeciallythese；
fortheyarethecausesthatoperateonsomuchofthedivineas
appearstous。Theremust，then，bethreetheoreticalphilosophies，
mathematics，physics，andwhatwemaycalltheology，sinceitis
obviousthatifthedivineispresentanywhere，itispresentin
thingsofthissort。Andthehighestsciencemustdealwiththe
highestgenus。Thus，whilethetheoreticalsciencesaremoretobe
desiredthantheothersciences，thisismoretobedesiredthanthe
othertheoreticalsciences。Foronemightraisethequestionwhether
firstphilosophyisuniversal，ordealswithonegenus，i。e。some
onekindofbeing；fornoteventhemathematicalsciencesareall
alikeinthisrespect，-geometryandastronomydealwithacertain
particularkindofthing，whileuniversalmathematicsappliesaliketo
all。Weanswerthatifthereisnosubstanceotherthanthosewhich
areformedbynature，naturalsciencewillbethefirstscience；but
ifthereisanimmovablesubstance，thescienceofthismustbe
priorandmustbefirstphilosophy，anduniversalinthisway，because
itisfirst。Anditwillbelongtothistoconsiderbeingqua
being-bothwhatitisandtheattributeswhichbelongtoitquabeing。
Butsincetheunqualifiedterm’being’hasseveralmeanings，of
whichonewasseen’tobetheaccidental，andanotherthetrue
’non-being’beingthefalse，whilebesidesthesetherearethe
figuresofpredicatione。g。the’what’，quality，quantity，place，
time，andanysimilarmeaningswhich’being’mayhave，andagain
besidesallthesethereisthatwhich’is’potentiallyor
actually:-since’being’hasmanymeanings，wemustsayregardingthe
accidental，thattherecanbenoscientifictreatmentofit。Thisis
confirmedbythefactthatnosciencepractical，productive，or
theoreticaltroublesitselfaboutit。Forontheonehandhewho
producesahousedoesnotproducealltheattributesthatcomeinto
beingalongwiththehouse；fortheseareinnumerable；thehouse
thathasbeenmademayquitewellbepleasantforsomepeople，hurtful
forsome，andusefultoothers，anddifferent-toputitshortlyfrom
allthingsthatare；andthescienceofbuildingdoesnotaimat
producinganyoftheseattributes。Andinthesamewaythegeometer
doesnotconsidertheattributeswhichattachthustofigures，nor
whether’triangle’isdifferentfrom’trianglewhoseanglesare
equaltotworightangles’-Andthishappensnaturallyenough；forthe
accidentalispracticallyamerename。AndsoPlatowasinasensenot
wronginrankingsophisticasdealingwiththatwhichisnot。For
theargumentsofthesophistsdeal，wemaysay，aboveallwiththe
accidental；e。g。thequestionwhether’musical’and’lettered’are
differentorthesame，andwhether’musicalCoriscus’and’Coriscus’
arethesame，andwhether’everythingwhichis，butisnoteternal，
hascometobe’，withtheparadoxicalconclusionthatifonewhowas
musicalhascometobelettered，hemustalsohavebeenletteredand
havecometobemusical，andalltheotherargumentsofthissort；the
accidentalisobviouslyakintonon-being。Andthisisclearalsofrom
argumentssuchasthefollowing:thingswhichareinanothersense
comeintobeingandpassoutofbeingbyaprocess，butthingswhich
areaccidentallydonot。Butstillwemust，asfaraswecan，say
further，regardingtheaccidental，whatitsnatureisandfromwhat
causeitproceeds；foritwillperhapsatthesametimebecomeclear
whythereisnoscienceofit。
Since，amongthingswhichare，somearealwaysinthesamestate
andareofnecessitynotnecessityinthesenseofcompulsionbut
thatwhichweassertofthingsbecausetheycannotbeotherwise，
andsomearenotofnecessitynoralways，butforthemostpart，
thisistheprincipleandthisthecauseoftheexistenceofthe
accidental；forthatwhichisneitheralwaysnorforthemostpart，we
callaccidental。Forinstance，ifinthedog-daysthereiswintry
andcoldweather，wesaythisisanaccident，butnotifthereis
sultryheat，becausethelatterisalwaysorforthemostpartso，but
nottheformer。Anditisanaccidentthatamanispaleforthis
isneitheralwaysnorforthemostpartso，butitisnotbyaccident
thatheisananimal。Andthatthebuilderproduceshealthisan
accident，becauseitisthenaturenotofthebuilderbutofthe
doctortodothis，-butthebuilderhappenedtobeadoctor。Again，a
confectioner，aimingatgivingpleasure，maymakesomethingwholesome，
butnotinvirtueoftheconfectioner’sart；andthereforewesay
’itwasanaccident’，andwhilethereisasenseinwhichhemakesit，
intheunqualifiedsensehedoesnot。Fortootherthingsanswer
facultiesproductiveofthem，buttoaccidentalresultsthere
correspondsnodeterminateartnorfaculty；forofthingswhichareor
cometobebyaccident，thecausealsoisaccidental。Therefore，since
notallthingseitherareorcometobeofnecessityandalways，
but，themajorityofthingsareforthemostpart，theaccidentalmust
exist；forinstanceapalemanisnotalwaysnorforthemostpart
musical，butsincethissometimeshappens，itmustbeaccidentalif
not，everythingwillbeofnecessity。Thematter，therefore，whichis
capableofbeingotherwisethanasitusuallyis，mustbethecauseof
theaccidental。Andwemusttakeasourstarting-pointthequestion
whetherthereisnothingthatisneitheralwaysnorforthemostpart。
Surelythisisimpossible。Thereis，then，besidesthesesomething
whichisfortuitousandaccidental。Butwhiletheusualexists，can
nothingbesaidtobealways，orarethereeternalthings？Thismust
beconsideredlater，’butthatthereisnoscienceoftheaccidental
isobvious；forallscienceiseitherofthatwhichisalwaysorof
thatwhichisforthemostpart。Forhowelseisonetolearnorto
teachanother？Thethingmustbedeterminedasoccurringeitheralways
orforthemostpart，e。g。thathoney-waterisusefulforapatientin
afeveristrueforthemostpart。Butthatwhichiscontraryto
theusuallawsciencewillbeunabletostate，i。e。whenthething
doesnothappen，e。g。’onthedayofnewmoon’；foreventhatwhich
happensonthedayofnewmoonhappenstheneitheralwaysorforthe
mostpart；buttheaccidentaliscontrarytosuchlaws。Wehave
stated，then，whattheaccidentalis，andfromwhatcauseitarises，
andthatthereisnosciencewhichdealswithit
Thatthereareprinciplesandcauseswhicharegenerableand
destructiblewithouteverbeingincourseofbeinggeneratedor
destroyed，isobvious。Forotherwiseallthingswillbeof
necessity，sincethatwhichisbeinggeneratedordestroyedmust
haveacausewhichisnotaccidentallyitscause。WillAexistornot？
ItwillifBhappens；andifnot，not。AndBwillexistifC
happens。Andthusiftimeisconstantlysubtractedfromalimited
extentoftime，onewillobviouslycometothepresent。Thisman，
then，willdiebyviolence，ifhegoesout；andhewilldothisif
hegetsthirsty；andhewillgetthirstyifsomethingelsehappens；
andthusweshallcometothatwhichisnowpresent，ortosomepast
event。Forinstance，hewillgooutifhegetsthirsty；andhewill
getthirstyifheiseatingpungentfood；andthisiseitherthe
caseornot；sothathewillofnecessitydie，orofnecessitynot
die。Andsimilarlyifonejumpsovertopastevents，thesame
accountwillholdgood；forthis-Imeanthepastcondition-is
alreadypresentinsomething。Everything，therefore，thatwillbe，
willbeofnecessity；e。g。itisnecessarythathewholivesshallone
daydie；foralreadysomeconditionhascomeintoexistence，e。g。
thepresenceofcontrariesinthesamebody。Butwhetherheisto
diebydiseaseorbyviolenceisnotyetdetermined，butdependson
thehappeningofsomethingelse。Clearlythentheprocessgoesbackto
acertainstarting-point，butthisnolongerpointstosomething
further。Thisthenwillbethestarting-pointforthefortuitous，
andwillhavenothingelseascauseofitscomingtobe。Buttowhat
sortofstarting-pointandwhatsortofcausewethusreferthe
fortuitous-whethertomatterortothepurposeortothemotivepower，
mustbecarefullyconsidered。
Letusdismissaccidentalbeing；forwehavesufficiently
determineditsnature。Butsincethatwhichisinthesenseofbeing
true，orisnotinthesenseofbeingfalse，dependsoncombination
andseparation，andtruthandfalsitytogetherdependonthe
allocationofapairofcontradictoryjudgementsforthetrue
judgementaffirmswherethesubjectandpredicatereallyarecombined，
anddenieswheretheyareseparated，whilethefalsejudgementhasthe
oppositeofthisallocation；itisanotherquestion，howithappens
thatwethinkthingstogetherorapart；by’together’and’apart’I
meanthinkingthemsothatthereisnosuccessioninthethoughts
buttheybecomeaunity；forfalsityandtrutharenotinthings-it
isnotasifthegoodweretrue，andthebadwereinitself
false-butinthought；whilewithregardtosimpleconceptsand’whats’
falsityandtruthdonotexisteveninthought——thisbeingso，wemust
considerlaterwhathastobediscussedwithregardtothatwhichis
orisnotinthissense。Butsincethecombinationandthe
separationareinthoughtandnotinthethings，andthatwhichis
inthissenseisadifferentsortof’being’fromthethingsthat
areinthefullsenseforthethoughtattachesorremoveseither
thesubject’s’what’oritshavingacertainqualityorquantityor
somethingelse，thatwhichisaccidentallyandthatwhichisinthe
senseofbeingtruemustbedismissed。Forthecauseoftheformer
isindeterminate，andthatofthelatterissomeaffectionofthe
thought，andbotharerelatedtotheremaininggenusofbeing，and
donotindicatetheexistenceofanyseparateclassofbeing。
Thereforeletthesebedismissed，andletusconsiderthecausesand
theprinciplesofbeingitself，quabeing。Itwasclearinour
discussionofthevariousmeaningsofterms，that’being’has
severalmeanings。