第2章
加入书架 A- A+
点击下载App,搜索"Geometry no Friend to Infidelity",免费读到尾

  Andthisholdsuniversallybethequantitiesaandbwhattheywill,bigorlittle,finiteorinfinitesimal,increments,moments,orvelocities。Norwillitavailtosaythatabisaquantityexceedingsmall:Sincewearetoldthatinrebusmathematiciserroresquamminiminonsuntcontemnendi。[Introduct。adQuadrat。Curv。]Suchreasoningasthis,fordemonstration,nothingbuttheobscurityofthesubjectcouldhaveencouragedorinducedthegreatauthorofthefluxionarymethodtoputuponhisfollowers,andnothingbutanimplicitedeferencetoauthoritycouldmovethemtoadmit。Thecaseindeedisdifficult。Therecanbenothingdonetillyouhavegotridofthequantityab。InordertothisthenotionofFluxionsisshifted:itisplacedinvariouslights:PointswhichshouldbeasclearasfirstPrinciplesarepuzzled;andtermswhichshouldbesteadilyusedareambiguous。Butnotwithstandingallthisaddressandskillthepointofgettingridofabcannotbeobtainedbylegitimatereasoning。’’ItisnowtimetohearSirIsaacNewton。

  Princip。Lib。IILemm。2。Cas。1。``RectangulumquodvismotuperpetuoauctumAB,ubidelateribusA&Bdeerantmomentorumdimidia&,fuitin,seu;&quamprimumlateraA&Balterismomentorumdimidiisauctasunt,evaditin,seu。Dehocrectangulosubducaturrectangulumprius,&manebitexcessusaBbA。Igiturlaterumincrementistotisa&bgeneraturrectanguliincrementumaBbA。Q。E。D。’’HavingnowfairlylaidbeforemyreaderwhatbothyourselfandSirIsaacNewtonhavedelivereduponthissubject,Icometoexaminewhichofyouisintheright。

  Inthefirstplace,IfindyoutakeitforgrantedthatwhatSirIsaacNewtonishereendeavouringtofind,bysupposingthesidesAandBfirsttowanthalftheirmoments,andafterwardstohavegainedtheotherhalvesoftheirmoments,istheincrementoftherectangleAB。

  InthisIconceiveyouaremistaken。Forneitherinthedemonstrationitself,norinanythingprecedingorfollowingit,isanymentionsomuchasoncemadeoftheincrementoftherectangleAB。Onthecontraryitplainlyappearsthatwhatheendeavourstoobtainbythesesuppositions,isnootherthantheincrementoftherectangle,andyoumustownhetakesthedirectandtruemethodtoobtainit。

  Butyouwillsay,isitnotthebusinessofthislemmatodeterminethemomentsofflowingquantities?AndisnotthedesignofCase1todeterminethemomentoftherectangleAB?Ianswerthatisisso:butthatrigorouslyspeakingthemomentoftherectangleAB,isnot,asyousuppose,theincrementoftherectangleAB;butitistheincrementoftherectangle。Inordertoclearupthispoint,Imustobserve,ThatthewordmomentisusedbySirIsaacNewtonandyourselftosignifieindifferentlyeitheranincrement,oradecrement。ThataBbAabisbyyoudemonstratedtobethetrueincrementoftherectangleAB。ThataBbA-abisthetruedecrementofthesamerectangleAB;asplainlyappearsupontakingthesametrueanddirectmethodforfindingthedecrement,asyouhaveusedforfindingtheincrement。Now,Sir,Iwouldhumblybegleavetoinquireofyou,whoseesomuchmoreclearlyintothesemattersthanSirIsaacNewtonoranyofhisfollowers;

  whichofthesetwoQuantitiesaBbAabandaBbA-ab,youwillbepleasedtocallthemomentoftherectangleAB?Thecaseindeedisdifficult,thedifferencebetweenthemisnolessthan2ab,justthedoubleofthesameab,whichhasgivenusallsomuchtrouble;andyeteachofthempleadanequalrighttothetitleofmoment。Soequalaone,that,thoughIamverysensibleofyouraddressandskill,yetthereseemstobenopossibilityofdecidingthecontroversybetweenthembylegitimatereasoning。

  Iseebuttwowaysofdoingit。Oneisthattheyshouldtossupcrossorpileforthetitle:OrifthatbethoughttooboyishandunbeseemingtheGravityofMathematicalquantities,theymustevenendthedisputeinanamicablemanner,andwithoutclaiminganypreferenceoneofanother,agreethattheymaketwomomentsbetweenthem。Then,Sir,Iapprehendthecasewillstandthus:aBbAabaBbA-abmakingtwicethemomentoftherectangleAB;itfollowsthataBbAwillmakethesinglemomentofthesamerectangle。

  Yousee,Sir,afterallthepainsyouhavetaken,thisaffaircomesout,evenuponyourownconcessions,justasSirIsaacNewtonandhisfollowerswouldhaveit。Believeme,thereisnoremedy。Youmustacquiesce。

  OnlyifitmaybeanySatisfactiontoyoutoknowwhySirIsaactookthisindirectwayoffindingtheincrementof,insteadofproceedingdirectlytofindthemomentoftherectangleAB,Ishallbereadytoobligeyouasfarascanbeexpectedfromoneofthose,whohaveshownthemselvesmoreeagerinapplyinghismethod,thanaccurateinexamininghisprinciples。

  Thefinalcauseormotivetothisproceeding,Ifind,isnotunknowntoyou;yousayitisveryobvious,meaning,Isuppose,thattherebyitwasintendedtoexcludethissametroublesomerectangleab。Whytruly,Sir,inabookofstrictdemonstration,asSirIsaacNewtonintendedhisPrincipiashouldbe,itwascertainlymorepropertoexcludethatquantity,soasnottosufferittoappear,thanfirsttointroduceitintothereader’sviewandthentorejectit。

  Youaddthatitisnotsoobviousoreasytoexplainajustandlegitimatereasonforit,orshewittobeGeometrical。Howfaritmaybeobviousoreasytoassignsuchareason,Iwillnotdispute:thoughIamapttothinkthatwhatiseasytome,cannotbedifficulttootherpersons,providedtheyusethesameendeavourstofindthetruthasIhavedone。NowIapprehendthereasonofthisproceedingofSirIsaacNewtontobethefollowingveryplainone:ThatinordertofindthemomentoftherectangleAB,itismoreconsonanttostrictGeometricalrigourtotaketheincrementoftherectangle,thantotaketheincrementoftherectangleABitself。AndifI

  canmakethisappear,youmustallowthathehadajustandlegitimatereasonforproceedingashedid。

  YouknowverywellthatthemomentoftherectangleABisproportionaltothevelocityofthatrectangle,withwhichitalters,eitherinincreasing,orindiminishing。Now,Iask,inGeometricalrigour,whatisproperlythevelocityofthisrectangle?IsitthevelocitywithwhichtherectanglefromABbecomes;

  orthevelocitywithwhichfromABitbecomes?

  IfindmyselfexactlyinthecaseoftheAssbetweenthetwobottlesofhay:Iseenoreason,norpossibilityofareasontodeterminemeeitheroneway,ortheother。ButmethinksIhearthevenerableGhostofSirIsaacNewtonwhisperme,thatthevelocityIseekfor,isneithertheonenortheotherofthese,butisthevelocitywhichtheflowingrectanglehas,notwhileitisgreaterorlessthanAB,neitherbefore,norafteritbecomesAB,butattheveryinstantoftimethatitisAB。InlikemannerthemomentofthisrectangleisneithertheincrementfromABto;

  norisitthedecrementfromABto:

  ItisnotamomentcommontoABand,whichmaybeconsideredasantheincrementoftheformer,orasthedecrementofthelatter:NorisitamomentcommontoABand,whichmaybeconsideredasthedecrementofthefirst,orastheincrementofthelast:ButitisthemomentoftheveryindividualrectangleABitself,andpeculiartothatonly;andsuchasbeingconsideredindifferentlyeitherasanincrementordecrement,shallbeexactlyandperfectlythesame。AndthewaytoobtainsuchamomentisnottolookforonelyingbetweenABand;

  nortolookforonelyingbetweenABand;

  thatis,nottosupposeABaslyingateitherextremityofthemoment;

  butasextendedtothemiddleofit;ashavingacquiredtheonehalfofthemoment,andasbeingabouttoacquiretheother;orashavinglostonehalfofit,andbeingabouttolosetheother。AndthisisthemethodSirIsaacNewtonhastakeninthedemonstrationyouexceptagainst。

  Whatsayyou,Sir?IsthisajustandlegitimatereasonforSirIsaac’sproceedingashedid?Ithinkyoumustacknowledgeittobeso。ForevenifyoushouldstillhaveanydoubtwhetherhisproceedingberigorouslyGeometrical;yetyoucannotbutconfessthatwhethermomentsbeconsideredasinfinitelysmall,orasfinitequantities,hismethodapproachesnearertoGeometrickrigour,thanthatwhichyoupropose。I

  thinklikewiseyoucannotbutbesensibleofgreatwantofcautioninyourownproceeding;inasmuchasthatquantity,whichSirIsaacNewtonthroughthiswholeLemma,andalltheseveralcasesofit,constantlycallsamoment,withoutconfiningittobeeitherincrementordecrement,isbyyouincosideratelyandarbitrarily,andwithoutanyshadowofreasongiven,supposedanddeterminedtobeanincrement。Andthis,Sir,naturallyleadsmetogiveyouapieceoffriendlyadvice,whichyouseemtostandmuchinneedof。Itisthat,wheneveryoutakeitintoyourheadtocriticiseuponSirIsaacNewton’swritings,youfirstexamineandweigheverywordheuses;andifyoutranslatehim,keepcloselytohisexpression。

  Believeme,thisGreatMan,amonghisotherextraordinaryindowments,hadapeculiarsagacityinforeseeingobjections,aswellasanaversiontodisputing。Tothesetwoqualitiesaccompaniedwithextremehumanityandcondescensionitisowing,thatheusessuchaccuracyinhisexpression,thatanintelligentandattentivereadercannevermistakehim;andthathedoesofhimselffirstpropose,andthenremovesuchdifficulties,asmaynaturallyariseinthemindsofevencandidandjudiciouspersons,whoarenotyetmastersofthesubjecthetreatsof。ButasfortheHominesstolidi&addepugnandumparati,hecontentshimselfwithobservingthatprudentcautionineverywordheuses,thatastheyshallfindnothingtomisleadthem,soontheotherhand,iftheyunreservedlyandunadvisedlyattackhim,theyshallcertainlyandunavoidablyinduereseinstimuloslatentes,andexposethemselvestothescornandcontemptofeveryunprejudicedobserver。

  Thisgreatexample,whichinanythelowestdegreetoimitateisthehighesthonourIcaneverarriveat,orevendesire,movesmetoproposeandremoveanobjectionwhichmaypossiblyariseinyourmind,andhinderyoufromacquiescinginonepartofwhatIhavejustnowlaidbeforeyou。

  ItisthatIhavesupposedtherectangleABextendedtothemiddleofitsmoment;ashavingacquiredthehalfofit,andbeingabouttoacquiretheother;orashavinglostonehalfofit,andbeingabouttolosetheother。Youmaysaythisisstrictlyandexactlytrueinrespectofthesidesofthatrectangle;whichsides,fromandarebecomeAandB;andareabouttobecomeand;

  butthatitisnotequallytrueoftherectanglecomposedofthosesides,whichfrom,or,isbecomeAB;andisabouttobecome,or:sincethepartofthemomentwhichABissupposedtohavegained,namely,isnotequaltothatpartofthemomentwhichisabouttobegained,namely;thedifferencebetweenthembeing。

  InanswertothisIreply,thatthesetwoquantities,andsolongasaandbarefinitequantities,areundoubtedlyunequal;butthatthemoreaandbarediminished,bysomuchnearerwillthesequantitiesapproachtoanequality;andifaandbarediminishedadinfinitum,thetwoquantitieswillthenbeperfectlyequal。SeethisdemonstratedPrincip。Lib。I。Sect。

  I。Lemm。I。WhichLemma,foryourownsakeandmine,Icouldwishyouhadconsultedsooner。

  Lastly,toremoveallscrupleanddifficultyaboutthisaffair,Imustobserve,thatthemomentoftherectangleAB,determinedbySirIsaacNewton,namelyaBbA,andtheincrementofthesamerectangle,determinedbyyourself,namelyaBbAab,areperfectlyandexactlyequal,supposingaandbtobediminishedadinfinitum;andthisbytheLemmajustnowquoted。

  Icomenowtoyoursecondinstanceoffalsereasoning,whichyoutakefromtheBookofQuadratures;andpassingbytheLemmayousogravelylaydowntoshew,thatwhentwocontrarysuppositionsaremade,nothingcanbeinferredfromeitherofthem;asatruththatnoSchool-boycanbeignorantof;Ishallheretranscribethisinstanceoffalsereasoningasyougiveit,withyourobservationsuponit。``Letthequantityxflowuniformly,andbeitproposedtofindtheFluxionof。

  Inthesametimethatxbyflowingbecomesxo,thepowerbecomes,i。e。bythemethodofinfiniteSeriesandtheincrementsoandaretooneanotheras1toLetnowtheincrementsvanish,andtheirlastproportionwillbe1to。

  Butitshouldseemthatthisreasoningisnotfairorconclusive。Forwhenitissaid,lettheincrementsvanish,i。e。lettheincrementsbenothing,orlettherebenoincrements,theformersuppositionthattheincrementsweresomething,orthattherewereincrements,isdestroyed,andyetaconsequenceofthatsupposition,i。e。anexpressiongotbyvirtuethereof,ifretained。Which,bytheforegoingLemma,isafalsewayofarguing。Certainlywhenwesupposetheincrementstovanish,wemustsupposetheirproportions,theirexpressions,andeverythingelsederivedfromthesuppositionoftheirexistencetovanishwiththem。’’

  [Analystp。20。]Youarepleasedtogoonforsomenumberofpages,tomakethispointplainer,tounfoldthereasoning,andtoproposeitinafullerlight。ButIthinkwemayaswellstophere。Youhavealreadysofullyunfoldedit,thatifthisbethewayofreasoningofourMathematicalInfidels,IpronounceourReligionoutofalldangerfromthatquarter。

  FromthistimeourReverendClergymaysleepinquiet,andbeunderaslittleapprehensionfromtheunbelievingAnalyst,asfromthemostignorantofthePopishMonks,themoststupidoftheJewishRabbi’s,orthemostemptyandcontemptiblepratersamongtheMinutePhilosophers。Ihaveonlyonedoubtuponme。Pray,Sir,areyouverysurethatthisistherealdoctrineofSirIsaacNewton?Areyouabsolutelycertainyouhavenotmistakenhim?Youseem,Imustconfess,tobeexceedinglycautious,youblameothersfornotbeingaccurateinexamininghisPrinciples,youtalkofpreventingallpossibilityofmistakingyou,andyoutreathimandhisfollowersinsuchamanner,thatyouaretoexpectnoquarterfromthemincaseofillsuccess。Andyetthisissogreat,sounaccountable,sohorrid,sotrulyBoeotianablunder,thatIknownothowtothinkaGreatGenius,aNewtoncouldbeguiltyofit。ForGod’ssakeletusexamineitoncemore。Evanescantjamaugmentailla,letnowtheincrementsvanish,i。e。lettheincrementsbenothing,orlettherebenoincrements。Hold,Sir,Idoubtwearenotrighthere。IrememberSirIsaacNewtonoftenusesthetermsofmomentanascentiaandmomentaevanescentia。IthinkIhaveseenyoulikewiseseveraltimesusingtheliketermsofnascentandevanescentincrements。Also,ifIamnotmistaken,bothheandyouconsideranascent,orevanescentmoment,incrementordecrement,asthesamequantityunderdifferentcircumstances;

  sometimesasinthepointofbeginningtoexist,andothertimesasinthepointofceasingtoexist。Fromthismethinksitshouldfollowthatthetwoexpressionssubjoined,willbeperfectlyequivalenttoeachother。Nascanturjamaugmentailla,&eorumratioprimaeritEvanescentjamaugmentailla,&eorumratioultimaeritThemeaningofthefirstcanpossiblybenootherthantoconsiderthefirstproportionbetweenthenascentaugments,inthepointoftheirbeginningtoexist。Mustnotthereforethemeaningofthelatterbetoconsiderthelastproportionbetweentheevanescentaugments,inthepointofevanescence,ortheirceasingtoexist?Oughtitnottobethustranslated,Lettheaugmentsnowbecomeevanescent,letthembeuponthepointofevanescence?

  Whatthenmustwethinkofyourinterpretation,Lettheincrementsbenothing,lettherebenoincrements?Donotthewordsratioultimastareusintheface,andplainlytellusthatthoughthereisalastproportionofevanescentincrements,yettherecanbenoproportionofincrementswhicharenothing,ofincrementswhichdonotexist?Ibelieve,Sir,everythinkingpersonwillacquitSirIsaacNewtonofthegrossoversightyouascribetohim,andwillacknowledgethatitisyourselfalone,whohavebeenguiltyofamostpalpable,inexcusable,andunpardonableblunder。

  Inowcometothethirdheadofyourobjections。

  3。ArtsandfallaciesusedbySirIsaacNewtontomakehisfalsereasoningpassuponhisfollowers。

  OnthisheadIshallnotneedtotakeupmuchofyourtime,becausehavingalreadyprovedthatSirIsaacNewtonwasnotguiltyoffalsereasoningintheinstancesyoualledge,Isupposenobodywillthinkhehadanyoccasiontomakeuseofartsandfallaciestoimposeuponhisfollowers。

  Butyouhaveoneobservationuponthishead,whichissoverysingular,thatIcannotbutthinkitworthyofparticularconsideration。Considering,sayyou,thevariousartsanddevicesusedbytheGreatAuthoroftheFluxionarymethod:inhowmanylightsheplacethhisFluxions:andinwhatdifferentwaysheattemptstodemonstratethesamepoint:onewouldbeinclinedtothinkhewashimselfsuspiciousofthejustnessofhisowndemonstrations:andthathewasnotenoughpleasedwithanyonenotionsteadilytoadheretoit。Thusmuchatleastisplain,thatheownedhimselfsatisfiedconcerningcertainpoints,whichneverthelesshecouldnotundertaketodemonstratetoothers。[Analystp。27。]Really,Sir,thisseemstobeveryhardusage。SirIsaacNewtonhasmadeanewandgreatdiscovery,bywhichhehasnotonlyout-donealltheGeometriciansthateverwentbeforehim,butcanenablesuchordinaryproficientsinMathematicks,asyouandme,tosurpassallthegreatmastersofantiquity:Heissogoodastoinstructusinthismethod;andbecauseitrequiressomepainsanddiscernmenttocomprehenditrightly,hesetsitinseveralvariouslights,thatbymeansofsomeofthesewemaynotfailofunderstandingit。Pray,Sir,haveyouandIanyreasontocomplainofthis?Formypart,Ithinkmyselfgreatlyobligedtohimforhiscondescension:Ifhehadnottakensomuchpainstoexplainhisdoctrine,IdoubtIshouldneverhaveunderstoodit。But,forGod’ssake,whatisityouareoffendedat,whodonotstillunderstandhim?Youareallinthedark,andyetareangryathisgivingyousomuchlight。SurelythefaultisnotinSirIsaacNewton,butinyourowneyes。Sothickadropserenehasquench’dtheirorbs,Ordimsuffusionveil’d。Butisnothehimself,sayyou,suspiciousofthejustnessofhisowndemonstrations?

  Pray,Sir,whenaDivineisinstructinghishearersinaweightyandimportantpointofReligion,iffromadesirethateveryoneshouldperfectlyunderstandhim,heisatpainstouseseveralarguments,andtosethisDoctrineinvariouslights;woulditbereasonable,orjust,orgratefulinanyofhisauditorstoinferfromthis,thatthePreacherwassuspiciousofthejustnessofhisownreasoning?Whenyou,afterallthedemonstrationsthathadbeengivenofthebeingofaGod,bythelearnedFathersoftheChurch,andbythewisestofthePhilosophersofallages,thoughtfittointroducethatnewandsingularoneofaVisualLanguage,woulditbefairinmetosupposethatyouweresuspiciousofalltheformerproofsoftheexistenceofaDeity,andleftthatgreatandimportanttruthtodependuponametaphoricalargument?Surelyoneargumentmaybejust,andconclusive,andperfectlysatisfactorytohimthatusesit;andyetthemattertreatedofmaybeofthatdifficulty,orofthatdignityandimportance,asnotonlytoadmitof,buttorequireseveralothersfortheinstructionandconvictionofhishearers。AndthusmuchmaysufficeforyourthirdandlastheadofobjectionsagainstSirIsaacNewtonandhisfollowers:OnlybeforeIconcludeImustadviseyoutocorrectonewordinyourextractfromhisLettertoMr。Collins,Nov。8,1676,[Analyst,p。27]orrathertogiveupthatextractintirely,asbeingofnomannerofservicetoyou。ThereisagreatdealofdifferencebetweensayingIcannotundertaketoproveathing,andIwillnotundertakeit。

  SirIsaac,inthatLettersays,Iwillnot:Andbesides,thepointtherementionedisnotthepointhereindebate;sothatyouhavenorighttodrawanyinferencefromthatpointtothis。

  HavingnowdonewitheverythingnecessarytothevindicationofSirIsaacNewtonandhisfollowers,andtherebydrivenyouentirelyoutofourintrenchments,IamconsideringwhetherIshouldsallyoutandattackyouinyourown。Youhavethrownupsomeworks,Isee,whichatadistancemakeaprettygoodappearance,andseemcapableofdefence:

  Butupontakinganearerviewofthem,Ijudgethemtobeveryslightanduntenable,andtobeguardedratherbyanew-raised,undisciplinedMilitia,thananythingofveteran,regularTroops;sothatitwouldnotbeverydifficulttocarrythembyassault。Butastheyseemratherdesignedforshew,thanuse,moretoamuseyourself,thananywaytoannoyus,Iamdeterminedtoleaveyouinpossessionofthem。

  OnlyyoursuppositionofadoubleerrorinthemethodofFluxions,[Analyst,p。31&seq。top。49。]andtheuseyoumakeofittoshewhowtrueconclusionsareobtainedfromfalseprinciples,bymeansoftwocontrarymistakesexactlycompensatingoneanother,hassomethinginitsoextraordinary,astorequireanddeserveaparticularconsideration。ThisdarlingPhantom,thisbelovedoffspringofyourteemingbrain,whichlikeMinervaissuingarmedfromtheheadofJupiter,herspearinonehand,andherShieldwiththeGorgon’sheadintheother,istoturnallourMathematiciansintostocks,andstones,andstatues,issetforthwithsomuchartandskill,andisdressedoutinsoadvantageousandpompousamanner,todrawtheattentionandtodazzletheimaginationofthespectators,thatitwouldbeunpardonableneglectandrudenessinmetopassitbyunregarded。

  Ishallnotthereforecontentmyselfwithsayingthatoneoftheseerrors[Seep。46-53。]isalreadybecomeevanescent,i。e。isnothing,isnoerroratall;andthattheotherofthemwilllikewiseimmediatelydisappearliketheGhostofadepartedquantity,[Analyst,p。59。]

  ifyouexorciseitwithafewwordsoutofthefirstsectionofthePrincipia:

  Onthecontrary,Iproposesofartogratifyyourfondnessforthishopefulscheme,astogiveitafairandfullexamination。

  Wearetoconsiderthereforewhatmaybethereason,thatinthemethodofFluxionstheconclusionsareexactlytrue:Forintheexactnessoftheconclusionswearebothagreed;thoughtherebeawidedifferencebetweenusinrespectofthemeansbywhichMathematiciansarriveatthatexactness。

  Iconceivethattheconclusionisthereforeexact,becauseitisdeducedbyjustreasoningfromcertainprinciples。YouonthecontraryareofopinionthatSirIsaacNewtonisguiltyofacapitalandfundamentalerroronrejectingthequantityab,sooftentalkedof,andthattheconclusioncomesoutright,notbecausethequantityrejectedisinfinitelysmall,butbecausethiserroriscompensatedbyanothercontraryandequalerror。[Analyst,p。35。]Andthisyousay,perhapstheDemonstratorhimselfneverkneworthoughtof。[p。36。]Ifhehadcommittedonlyoneerror,hewouldnothavecomeatatruesolutionoftheProblem。Butbyvirtueofatwo-foldmistakehearrives,thoughnotatscience,yetattruth。Forscienceitcannotbecalled,whenheproceedsblindfold,andarrivesatthetruthnotknowinghoworbywhatmeans。[p。34。]

  Thisisthewayyouaccountforwhatyoujustlysay,mayperhapsseemanunaccountableParadox,thatMathematiciansshoulddeducetruePropositionsfromfalsePrinciples,berightintheconclusion,andyeterrinthepremisses;

  thaterrorshouldbringforthtruth,thoughitcannotbringforthscience。

  [p。31。]

  Nowtruly,Sir,ifthisParadoxofyourshouldbewellmadeout,ImustconfessitoughtverymuchtoaltertheopiniontheworldhashadofSirIsaacNewton,andoccasionourtalkingofhiminaverydifferentmannerfromwhatwehavehithertodone。Whatthinkyouif,insteadofthegreatestthateverwas,weshouldcallhimthemostfortunate,themostluckyMathematicianthateverdrewacircle?MethinksIseethegoodoldGentlemanfastasleepandsnoringinhiseasychair,whileDameFortuneisbringinghimherapronfullofbeautifulTheoremsandProblemswhichheneverknowsorthinksof:justastheAtheniansoncepaintedherdraggingtownsandcitiestoherfavouriteGeneral。Forwhatelsebutextremegoodfortunecouldoccasiontheconclusionsarisingfromhismethodtobealwaystrueandjustandaccurate,whenthepremisseswereinaccurateanderroneousandfalse,andonlyledtorightconclusionsbymeansoftwoerrorsevercompensatingoneanothertotheutmostexactness?Whatluckwashere?Thatwhenhehadmadeonecapital,fundamental,generalmistake,heshouldhappentomakeasecond,ascapital,asfundamental,asgeneralasthefirst;Thatheshouldnotproceedtocommitthreeorfoursuchmistakes,butstopatthesecond:Thatthesetwomistakesshouldchancetolieboththesameway,butoncontrarysides,sothattheonemighthelptocorrecttheother;andlastly,thatthetwocontraryerrors,amongalltheinfiniteproportionswhichtheymightbeartooneanother,shouldhappenuponthatofaperfectequality;sothatonemightinallpossiblecasesbeexactlybalancedorcompensatedbytheother。Withaquarterofthisgoodfortuneamanmightgetthe10000l。prizeinthepresentLottery,withasingleTicket。

  Buttocometoourpoint,wearetoexaminewhethertheexactnessoftheconclusionisowingtotheexactcompensationofoneoftheseerrorsbytheother,ortothoseerrorsbeingutterlyinsignificant,beinginrealitynoerrorsatall。AndinordertheretoIproposetoseehowtheconclusionwillcomeout,whenonlyoneoftheseerrorsiscommitted,sothatthereisnothingtocompensateit。

  Inyour21section,whichwithitsfigureIherereferto,thefirsterrorissupposedtobethemakingthesubtangentorinsteadofTheseconderrorismakinginsteadofIfboththeseerrorsbecommitted,orifneitherofthembecommitted,theconclusionisagreedtobeequallyjustandright,givingS=2x。

  IfIavoidthefirstoftheseerrors,bymakingandretainthesecond,bysupposingmyconclusionwillbeOntheotherhandifIcommitthefirsterror,andavoidthesecond,myconclusionwillgivemeNowIaffirmthatthesetwoseveralvaluesofS,whicharetheresultofoneerroronlywithoutanythingtocompensateit,arebothtrueandequallyexactwiththeformervalue,2x,whichistheresultofeitheroftwoerrors,orofnoneatall。You,Iamsensible,willdisputethiswithme,youwillsaythatoneofthese,islessthan2x;andthelatter,isinthesameproportionbiggerthan2x。Ibegleavetherefore,fortheinformationofsomeofmyreaders,toaskyouaquestion。Supposingthetruesubtangent2xtobeathousandmilesinlength,howmuchwillthesecondvalueofthatsubtangentfallshortofathousandmiles?Willitbeayard,orafoot,oraninch?

  Noneoftheseyouconfess,northethousandth,northethousand-millionthpartofaninch。

  Iaskfurther,whatthenisthisdifference?Isitpossibleinalltheinfinityoffractionalnumberstofindanythingsmallenoughtorepresentit?Youown,youconfessitisnot:Youmustconfesslikewise,thatifthesethreeseveralvaluesofSwerealltobeexpressedinnumbers,withoutbeingreducibletowhich,inyouropinion,[AnalystQuery24。]

  theycanbeofnouse,theymusteveryonebeexpressedby1000,withouttheleasttittleofvariation,addition,ordiminution。Behold,GentleReader,whatamightybeam[MottotoAnalyst。]herehasbeendiscoveredintheeyesofMathematicians,incomparisonwithwhichallthedifficultiesinDivinityarebutasmotesandatoms!

  Sincethereforetheseerrorsarewhollyinsignificant,myconclusionwhenreducedtonumbers,comingoutexactlythesame,whetherthefirst,orsecond,orneither,orbothoftheseerrorsbecommitted;andsincebycommittingboththeseerrors,thecalculus,whichwouldotherwise,especiallyinthehigheroperations,beexceedinglytediousandlaborious,isnowrenderedsurprisinglyexpeditiousandeasy;itseemstomethatthisissofarfrombeinganydefectinthemethodofFluxions,thatonthecontraryitisoneofthegreatestadvantagesandexcellenciesofthatinvention。

  Butyoutellmeitisnottheusefulnessofthismethodthatisthematterindispute:allthequestioniswhetheritbescientifical,whetherthosewhouseit,seetheirwaydistinctly,orproceedblindfoldandarriveatthetruthnotknowinghoworbywhatmeans。Ihavespokentothisbefore,butmustaddawordortwomoreinthisplace。You,Sir,areforavoidingthesetwoerrors;Iamforretainingthem。Whenyouavoidthem,donotyouseeyourwaydistinctly?AndifIretainthem,voluntarily,andwithmyeyesopen;mayInotneverthelessclearlyseetheeffectoftheseerrors,orofeitherofthem,ineverystepItakeandintheconclusionIatlastcometo?MayInotthereforelikewisebesaidtoseemywaydistinctly?Now,ifyouandIcanseeourwaysowell,Iamafraiditwillbeconstruedasgreatpresumptioninustosupposethatnobodydoessobesidesourselves:andmuchmore,ifweshouldsaythattheGreatInventorofthismethod,andtheAuthorofsomanyotherwonderfuldiscoveries,neverkneworthoughtofwhattousappearssoplainandmanifest;

  thathewhogaveussomuchlight,wasinthedarkhimself;thathewhoopenedourEyes,hadnosightofhisown。FormypartIcanneverconcurwithyouinthinkingthatIseefarther,orgobeyondSirIsaacNewton:Sedlongesequor,&vestigiapronusadoro。Butifyouthinkfittopersistinassertingthatthisaffairofadoubleerrorisentirelyanewdiscoveryofyourown,whichSirIsaacandhisfollowersneverkneworthoughtof,Ihaveunquestionableevidencetoconvinceyouofthecontrary。Imustacquaintyouthereforewithwhatallhisfollowersarealreadyapprisedof,thattheseveryobjectionsofyourswerelongsinceforeseen,andclearlyandfullyremovedbySirIsaacNewton,inthefirstsectionofthefirstbookofhisPrincipia;

  thegreaterpartofwhichsection,particularlythefirstandseventhLemma,andthatadmirableScholiumattheendofit,waswrittentothisveryendandpurposeonly,andtonootherintheworld。

  Ihavenownomoretodo,butonlytoacquitmyselfofthepromiseImadeawhileago,torectifyamistakeyouarefallenintowithregardtoanotherofthegreatestmentheEnglishnationhasproduced。InordertowhichImustheretranscribethegreaterpartoftheCXXXVarticleofyourNewTheoryofVision。``AfterreiteratedendeavourstoapprehendthegeneralIdeaofaTriangle,Ihavefounditaltogetherincomprehensible。AndsurelyitanyonewereabletointroducethatIdeaintomyMind,itmustbetheAuthoroftheEssayconcerningHumanUnderstanding;He,whohassofardistinguishedhimselffromthegeneralityofWriters,bytheclearnessandsignificancyofwhathesays。LetusthereforeseehowthiscelebratedAuthordescribesthegeneral,orabstractIdeaofaTriangle。Itmustbe,sayshe,neitherOblique,norRectangular,neitherEquilateral,Equicrural,norScalenum;butallandnoneoftheseatonce。Ineffectitissomewhatimperfectthatcannotexist;anIdea,whereinsomepartsofseveraldifferentandinconsistentIdeasareputtogether。EssayonHumanUnderstanding。B。iv。C。7。S。9。ThisistheIdea,whichhethinksneedfulfortheEnlargementofKnowledge,whichisthesubjectofMathematicalDemonstration,andwithoutwhichwecouldnevercometoknowanygeneralPropositionconcerningTriangles。ThatAuthoracknowledgesitdothrequiresomepainsandskilltoformthisgeneralIdeaofaTriangle。Ibid。

  Buthadhecalledtomindwhathesaysinanotherplace;towit,theIdeasofmixedModeswhereinanyinconsistentIdeasareputtogether,cannotsomuchasexistinthemind,i。e。beconceived。Vid。B。III。

  C。10。S。33。Ibid。Isay,hadthisoccurredtohisThoughtsitisnotimprobablehewouldhaveowneditaboveallthePainsandSkillhewasmasterof,toformtheabove-mentionedIdeaofaTriangle,whichismadeupofmanifest,staringcontradictions。ThataManwhothoughtsomuch,andlaidsogreatastressonclearanddeterminateIdeas,shouldneverthelesstalkatthisrateseemsverysurprising。’’InthissectionyouplainlyaccuseMr。Lockeofcontradictinghimselfintwoseveralparticulars。Theabove-mentionedIdeaofaTriangle,sayyou,ismadeupofmanifest,staringcontradictions。YourepresentthetwofollowingpropositionsofMr。Lockeascontradictoryonetotheother。It,thegeneralIdeaofaTriangle,isanIdea,whereinsomepartsofseveraldifferentandinconsistentIdeasareputtogether。

  Ideasofmixedmodes,whereinanyinconsistentideasareputtogether,cannotsomuchasexistintheMind。

  Iproposetoclearupthesetwopoints,andtoshewthatinneitherofthemMr。Lockeisguiltyofcontradictinghimself:butfirst,inorderthereto,Imusttakeupalittleofyourtimeinconsideringthenotionofgeneral,orabstractIdeas。WhichpainsIamtheratherinclinedtotakebecause,thoughIhavecarefullyperusedwhatyouhavewrittenuponthissubject,Iamoneofthosewhostilladheretothevulgar,orratheruniversalerrorofallMankind,thatneitherGeometry,noranyothergeneralsciencecansubsistwithoutgeneralIdeas。

  ThoughthewordsabstractorgeneralIdeasareindifferentlyusedbyWritersashavingthesamecommonsignification;yetasitmaybeameansofrenderingwhatIhavetosayuponthissubjectsomethingmoreintelligible,Ishallbegleavetomakeadistinctionbetweenthem,notasbeingdifferentinthemselves,butonlyinrespectofthemannerinwhichtheyarecommonlyformedorintroducedintothemind。

  IshallconfinethenameofabstractIdeatothat,whichthemindformstoitselffromtheconsiderationofsomenumberofdifferentspecies,byabstractingfromthoseparticularIdeasinwhichthespeciesdifferfromoneanother,andretainingthoseinwhichtheyagree。

  IshallcallthatageneralIdea,whichmaybeproducedinthemindwithoutanyconsideration,orevenknowledge,ofdifferentSpecies。

  Anexamplewillmakethisveryplain。WhenMr。RayisforminghisMethodofPlants,heobservesthatMint,andSage,andLavender,andRosemary,andmanyotherPlants,besidestheirparticularcharacteristicksbywhichtheyaredistinguishedfromoneanother,havesomeothermarksinwhichtheyallagree;asintheirleavesgrowinginpairsoppositetoeachother,amonopetalouslabiateflower,withfourseedsgrowingatthebottomofit,andthoseinclosedinnoothervesselthantheperianthium。

  ByjoiningtogetherthesecommonmarksheformshiscompoundIdeaofthatGenusofPlantswhichhecallsverticillate:whichfromhislayingaside,orabstractingfromallthepeculiardistinguishingmarksoftheseveralspecies,isproperlynamedanabstractIdea。

  ButifMr。RaywillteachmeBotanybyhisMethod,hemusttakeadifferentcourse;hemustbeginwithmewherehehimselfended;hemustfirstintroduceintomymindthegeneralIdeaofaverticillateplant,andafterwarddescendtoparticularspecies。Hetellsmethataverticillateplantisonewhoseleavesgrowinpairsoppositetoeachother,andwhoseflowerismonopetalousandlabiate,withfourseedsatthebottomofit,andthoseinclosedonlyintheperianthium。ThisinmeisproperlycalledageneralIdea,becauseIshallfindittocomprehendalltheparticularspeciesofverticillateplants:butIhavenoreasontocallitanabstractIdea,becausenotknowingasyetanyoftheparticularspecies,ortheircharacteristickdifferences,Ihavenothingtoabstractfrom。

  TheabstractIdeaisthatoftheMasterorPhilosopher;andthegeneralIdeathatoftheDisciple。Theformerrequires,asMr。Lockeobserves,somepainsandskilltoformit:thelatterdemandsneitherpainsnorskill,itneedsonlyalittleattentiontoconceiveit。

  InlikemannerifapersonacquaintedwiththeseveralspeciesofTriangles,isfromtheconsiderationofthesetoformanIdeaofaTriangleingeneral;

  hismethodwillbetoexaminetheseveralcompoundIdeasofthedifferentspeciesofTriangles,andtodistinguishbetweensuchpartsofthosecompoundIdeasasarethepeculiarcharacteristicksofeachspecies,andsuchpartsasarecommontoallofthemingeneral。ThenconnectingtheselasttogetherintoanewcompoundIdea,andabstractingfromalltherest,hewillhavetheabstractIdeaofaTriangle;whichisthatofaspacecomprehendedbythreerightlines,addifyouplease,containingthreeangles。

  WhenhehasgotthisIdeahimself,itistheeasiestthingintheworld,togiveittoanother。LethimtakeaLearner,aBoy,suppose,whohasneverlearnedwhatatriangleis,muchlesswhatanyparticularspeciesofTriangleis,andtellhimaTriangleisaspacecomprehendedbythreerightlines:IsaythattheBoy,assoonasheunderstandsthemeaningofthesewords,willhaveacquiredthegeneralIdeaofaTriangle。Ifyoudoubtofit,shewhimarectangularTriangledrawnuponpaper,andaskhimwhatitis;hewillwithouthesitationtellyouitisaTriangle:afterwardsshewhimseparatelyalltheotherspeciesofTriangles,andyouwillfindheknowsthemeveryonetobeaTriangle。HisIdeaofaTrianglethereforeisgeneral,inasmuchasitsuitalltheparticularspecies。AndtheacquiringthisIdeaeitherabstract,orgeneral,inTeacherorScholar,seemstometobeattendedwithsolittledifficulty,thatIthinkMr。Lockehassaidfullenoughwhenhedeclaresthatthefirstrequiressomepainsandskilltoformit:anditistomesurprisingtohearaGentlemanofyourpenetrationprofessthatafterreiteratedendeavourstoapprehendthegeneralIdeaofaTriangle,youhavefounditaltogetherincomprehensible。

  PutyourselfbutonceinthecaseofaLearner,endeavourtodivestyourmindofallyourpreconceivedGeometricalIdeas,andthenturntoEuclid’sdefinitions;andI’llventuretoassureyou,youwillfindnomoredifficultyinapprehendingthegeneralIdeaofaTriangle,thaninapprehendingtheIdeaofanobliqueangled,orofascaleneTriangle,oreventhatofanAnglealone;therebeingnoobjectionagainstthefirst,butwhatmaywithequalreasonbebroughtagainstanyoftheothers;aswilleasilyappeartohimthatconsiders,thatanangleingeneral,anobliqueangledTriangleingeneral,andascaleneTriangleingeneralcannowhereexistbutinIdeaonly,anymorethanaTriangleingeneral。

  Havingpremisedthusmuchconcerningtheabstract,orgeneralIdeaofaTriangle,IcomenowtoexamineintoyourchargeagainstMr。Locke,andinthefirstplaceImusttakenoticethatthischargeisintroducedinanunfairandunjustmanner。IfanyonewereabletointroducethatIdeaintomymind;sayyou,itmustbetheAuthoroftheEssayconcerningHumanUnderstanding;&c。LetusthereforeseehowthiscelebratedAuthordescribesthegeneral,orabstractIdeaofaTriangle。WouldnotanybodyimaginefromthesewordsthatMr。LockewereherepurposelydescribingthisIdea,inordertointroduceitintothemindofonewhohaditnotalready?Ifthatwerehisintention,itiscertainlyamostmiserabledescription;sincenopersonlivingwhodoesnotalreadyknowwhataTriangleis,caneverhavethatIdeaintroducedintohismindfromwhatMr。Lockeherelaysdown。AndyetthatIdeaisintroducedintothemindwithalltheeaseintheworldbywhathegivesustounderstandinanotherplace,[EssayonHum。Underst。B。II。C。31。

  S。6。]thattheIdeaofaTriangleisthatofthreelines,includingaspace。Couldhepossiblytalksoclearlyinoneplace,andsocloudilyinanother,ifhisintentionwerethesameinboth?Isitnotplaintoanyonewhoattentivelyreadsthepassageyoureferto,thathisintentiontherewasnottodescribethegeneralIdeaofaTriangle,butonlytoshewfromtheseeminginconsistenciesinthatIdea,supposedtobealreadyknown,thatitrequiredsomepainsandskilltoformit,aswellasotherabstractIdeas?Observehiswords,``ForabstractIdeasarenotsoobviousoreasytochildren,ortheyetunexercisedmind,asparticularones。Iftheyseemsotogrownmen,’tisonlybecausebyconstantandfamiliarusetheyaremadeso。Forwhenwenicelyreflectuponthem,weshallfind,thatgeneralIdeasarefictionsandcontrivancesofthemind,thatcarrydifficultywiththem,anddonotsoeasilyofferthemselves,asweareapttoimagine。Forexample,DoesitnotrequiresomepainsandskilltoformthegeneralIdeaofaTriangle?(Whichyetisnoneofthemostabstract,comprehensiveanddifficult。)

  Foritmustbeneitheroblique,norrectangle,neitherequilateral,equicrucialnorscalenon;butallandnoneoftheseatonce。Ineffect,itissomethingimperfect,thatcannotexist;anIdeawhereinsomepartsofseveraldifferentandinconsistentIdeasareputtogether。’’Wecomenowtothemanifest,staringcontradictions,containedinthisIdeaofaTriangle:thefirstofwhich,Isuppose,iscontainedinthesewords,allandnoneoftheseatonce。TheEnantiosis,Iconfess,isprettystrong:andyetthemeaningofitisplainlynomorethanthis,thatthegeneralIdeaofaTriangleisapartoftheIdeaofeveryspeciesofTriangleshereenumerated,butisnottheintireIdeaofanyoneofthem;iscommontothemall,andconfinedtonone。Itissomethingimperfectthatcannotexist,maypossiblybeanotherofyourcontradictions。

  Itdoesnotappearsotome。ForeveryindividualTriangle,everyTrianglethatcanexist,mustbesomethingmorethanaspaceincludedbythreelines,itmustalsohavethecharacteristickmarkofsomeoneoftheparticularspeciesofTriangles;withoutwhichitwouldbeimperfect,itcouldnotexist,whichiswhatMr。LockeheresaysofaTriangleingeneral。

  2。Butthegreatcontradictionofallseemstolieinthetwofollowingpropositions,whicharebroughttogetherfromdifferentpartsofMr。Locke’sworks,andsettostareoneanotherinthefacetodisgracetheirAuthor。

  ItisanIdea,whereinsomepartsofseveraldifferentandinconsistentIdeasareputtogether。

  Ideasofmixedmodes,whereinanyinconsistentIdeasareputtogether,cannotsomuchasexistinthemind。

  Here,Sir,Istronglyapprehendyouarefallenintooneofthosetraps,whichthisGreatManwouldsometimesdiverthimselfwithsettingtocatchunwarycavillers,theHominesstolidos&addepugnandumparatos,thatImentionedawhileago。Hadhisfirstpropositionrunthus,ItisanIdea,whereinseveraldifferentandinconsistentIdeasareputtogether,itwouldundoubtedlyhavebeencontradictorytothesecond。Butthatisnotthecase:prayobservethewordsofthiscautiousandaccurateWriter。

  ItisanIdea,whereinSOMEPARTSOFseveraldifferentandinconsistentIdeasareputtogether。Now,weknowthattheseveralcompoundIdeasofarectangled,andoblique,andanacuteangledTrianglearedifferentandinconsistentonewithanother。Notwoofthemcanbeputtogethersoasjointlytoexistorbeconceivedinthemind。LikewisetheseveralcompoundIdeasofanequilateral,equicrural,andscalenetriangleareinconsistentwithoneanother。ButyetsomepartsofoneoftheseinconsistentIdeasarenotonlyconsistent,butareperfectlythesamewithsomepartsofanother。ToshewthisIbegleavetodividetwooftheseinconsistentIdeasintoseveralparts。ThecompoundIdeaThecompoundIdeaofarectangledTriangleofanacuteangledTrianglemaybedividedintomaybedividedintotheseparts。theseparts。

  1。Aplainspace,1。Aplainspace,2。Comprehendedbyright2。Comprehendedbyrightlines,lines,3。Threeinnumber,3。Threeinnumber,4。Containingthreeangles,4。Containingthreeangles,5。Oneright,twoacute。5。Allacute。Thereis,wesee,nodifferencebetweenthefourfirstpartsofthecompoundIdeaofarectangledTriangle,andthefourfirstpartsofthatofanacuteangledTriangle:itisowingtothefifthpartaloneofeachIdea,thatthesetwoIdeasaredifferentandinconsistent。AndasitiseasytoseethatthesefourfirstpartsarethesameinallotherspeciesofTriangles;

  andthatthesamefourpartsdocomposethegeneralIdeaofaTriangle;

  itisplainthatthegeneralIdeaofaTriangleisanIdea,whereinSOME

  PARTSofseveraldifferentandinconsistentIdeasareputtogether。

  Thefirstthereforeofthetwopropositionsisquestionisundoubtedlytrue;andasthesepartsareinnowayinconsistentwithoneanother,itismanifestthatthesecondpropositionisnotcontradictory,oratallrepugnanttothefirst。

  Icomenow,Sir,totakemyleaveofyou,andhopethatifanhonestzealfortruthinthefirstplace,andinthesecondforthereputationofthoseGentlementowhomIconceivethewholebodyofmankind,atleastImustacknowledgemyselftobehighlyindebted,hasgivenoccasionnotonlyofdifferingfromyou,butevenofreprehendingyouwiththeutmostfreedomwhereverIthoughtthetruthandyourbehaviourrequiredit;youwillnotimputethelibertyIhavetakentoanydisrespectforyourperson,whichIamanutterstrangerto,thoughIhaveaverygreatesteemandvalueforyouruncommonabilitiesandmanyofyourwritings,andamwithsincererespect,SIR,Yourmostobedient,HumbleServant,PHILALETHESCANTABRIGIENSIS。FINIS。

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