andconsideredinthe`Analyst。’Andherethequestionbetweenusis,whetherIhaverightlyrepresentedthesenseofthosewordsevanescantjamaugmentailla,inrenderingthem,``lettheincrementsvanish,’’i。e。lettheincrementsbenothing,orlettherebenoincrements?Thisyoudeny;but,asyourmanneris,insteadofgivingareasonyoudeclaim。I,onthecontrary,affirm,theincrementsmustbeunderstoodtobequitegone,andabsolutelynothingatall。Myreasonis,becausewithoutthatsuppositionyoucanneverbringthequantityorexpressiondownto,theverythingaimedatbysupposingtheevanescence。Saywhetherthisbenotthetruthofthecase?Whethertheformerexpressionisnottobereducedtothelatter?
Andwhetherthiscanpossiblybedonesolongasoisarealquantity?
Icannotindeedsayyouarescrupulousaboutyouraffirmations,andyetIbelievethatevenyouwillnotaffirmthis;itbeingmostevident,thattheproductoftworealquantitiesissomethingreal;andthatnothingrealcanberejectedeitheraccordingtotheofgeometry,oraccordingtoSirIsaac’sownPrinciples;forthetruthofwhichIappealtoallwhoknowanythingofthesematters。Further,byevanescentmusteitherbemeant,letthem(theincrements)vanishandbecomenothing,intheobvioussense,orletthembecomeinfinitelysmall。ButthatthislatterisnotSirIsaac’ssenseisevidentfromhisownwordsintheverysamepage,thatis,inthelastofhis`IntroductiontotheQuadratures,’whereheexpresslysaith,voluiostenderequodinmethodofluxionumnonopussitfigurasinfiniteparvasingeometriamintroducere。Uponthewhole,youseemtohaveconsideredthisaffairsoverysuperficiallyasgreatlytoconfirmmeintheopinionyouaresoangrywith,towit,thatSirIsaac’sfollowersaremuchmoreeagerinapplyinghismethodthanaccurateinexamininghisprinciples。Youraiseadustaboutevanescentaugments,whichmayperhapsamuseandamazeyourreader,butIammuchmistakenifiteverinstructsorenlightenshim。For,tocometothepoint,thoseevanescentaugmentseitherarerealquantities,ortheyarenot。Ifyousaytheyare;Idesiretoknowhowyougetridoftherejectaneousquantity?Ifyousaytheyarenot;youindeedgetridofthosequantitiesinthecompositionwhereoftheyarecoefficients;butthenyouareofthesameopinionwithme,whichopinionyouarepleasedtocall(p。58)``amostpalpable,inexcusable,andunpardonableblunder,’’
althoughitbeatruthmostpalpablyevident。
34。Nothing,Isay,canbeplainertoanyimpartialreaderthanthat,bytheevanescenceofaugmentsintheabove—citedpassage,SirIsaacmeanstheirbeingactuallyreducedtonothing。But,toputitoutofalldoubtthatthisisthetruth,andtoconvinceevenyou,whoshewsolittledispositiontobeconvinced,Idesireyoutolookintohis``AnalysisperAequationesInfinitas’’(p。20),where,inhispreparationfordemonstratingthefirstruleforthesquaringofsimplecurves,youwillfindthat,onaparalleloccasion,speakingofanaugmentwhichissupposedtovanish,heinterpretsthewordevanescerebyessenihil。Nothingcanbeplainerthanthis,whichatoncedestroysyourdefence。Andyet,plainasitis,Idespairofmakingyouacknowledgeit;