首页 >出版文学> Geometry no Friend to Infidelity>第2章
  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。