Ofthingswhichchange，somechangeinanaccidentalsense，like
　　thatinwhich’themusical’maybesaidtowalk，andothersare
　　said，withoutqualification，tochange，becausesomethinginthem
　　changes，i。e。thethingsthatchangeinparts；thebodybecomes
　　healthy，becausetheeyedoes。Butthereissomethingwhichisby
　　itsownnaturemoveddirectly，andthisistheessentiallymovable。
　　Thesamedistinctionisfoundinthecaseofthemover；forit
　　causesmovementeitherinanaccidentalsenseorinrespectofa
　　partofitselforessentially。Thereissomethingthatdirectlycauses
　　movement；andthereissomethingthatismoved，alsothetimeinwhich
　　itismoved，andthatfromwhichandthatintowhichitismoved。
　　Buttheformsandtheaffectionsandtheplace，whicharethe
　　terminalsofthemovementofmovingthings，areunmovable，e。g。
　　knowledgeorheat；itisnotheatthatisamovement，butheating。
　　Changewhichisnotaccidentalisfoundnotinallthings，butbetween
　　contraries，andtheirintermediates，andbetweencontradictories。We
　　mayconvinceourselvesofthisbyinduction。
　　Thatwhichchangeschangeseitherfrompositiveintopositive，
　　orfromnegativeintonegative，orfrompositiveintonegative，or
　　fromnegativeintopositive。BypositiveImeanthatwhichis
　　expressedbyanaffirmativeterm。Thereforetheremustbethree
　　changes；thatfromnegativeintonegativeisnotchange，because
　　sincethetermsareneithercontrariesnorcontradictoriesthere
　　isnoopposition。Thechangefromthenegativeintothepositivewhich
　　isitscontradictoryisgeneration-absolutechangeabsolute
　　generation，andpartialchangepartialgeneration；andthechangefrom
　　positivetonegativeisdestruction-absolutechangeabsolute
　　destruction，andpartialchangepartialdestruction。If，then，’that
　　whichisnot’hasseveralsenses，andmovementcanattachneitherto
　　thatwhichimpliesputtingtogetherorseparating，nortothatwhich
　　impliespotencyandisopposedtothatwhichisinthefullsense
　　true，thenot-whiteornot-goodcanbemovedincidentally，forthe
　　not-whitemightbeaman；butthatwhichisnotaparticularthing
　　atallcaninnowisebemoved，thatwhichisnotcannotbemoved
　　andifthisisso，generationcannotbemovement；forthatwhichis
　　notisgenerated；forevenifweadmittothefullthatitsgeneration
　　isaccidental，yetitistruetosaythat’not-being’ispredicableof
　　thatwhichisgeneratedabsolutely。Similarlyrestcannotbelong
　　tothatwhichisnot。Theseconsequences，then，turnouttobe
　　awkward，andalsothis，thateverythingthatismovedisinaplace，
　　butthatwhichisnotisnotinaplace；forthenitwouldbe
　　somewhere。Norisdestructionmovement；forthecontraryofmovement
　　isrest，butthecontraryofdestructionisgeneration。Sinceevery
　　movementisachange，andthekindsofchangearethethreenamed
　　above，andofthesethoseinthewayofgenerationanddestructionare
　　notmovements，andthesearethechangesfromathingtoits
　　contradictory，itfollowsthatonlythechangefrompositiveinto
　　positiveismovement。Andthepositivesareeithercontraryor
　　intermediateforevenprivationmustberegardedascontrary，and
　　areexpressedbyanaffirmativeterm，e。g。’naked’or’toothless’or
　　Ifthecategoriesareclassifiedassubstance，quality，place，
　　actingorbeingactedon，relation，quantity，theremustbethree
　　kindsofmovement-ofquality，ofquantity，ofplace。Thereisno
　　movementinrespectofsubstancebecausethereisnothingcontraryto
　　substance，norofrelationforitispossiblethatifoneoftwo
　　thingsinrelationchanges，therelativetermwhichwastrueofthe
　　otherthingceasestobetrue，thoughthisotherdoesnotchangeat
　　all，-sothattheirmovementisaccidental，norofagentand
　　patient，ormoverandmoved，becausethereisnomovementof
　　movementnorgenerationofgeneration，nor，ingeneral，changeof
　　change。Fortheremightbemovementofmovementintwosenses；1
　　movementmightbethesubjectmoved，asamanismovedbecausehe
　　changesfrompaletodark，-sothatonthisshowingmovement，too，
　　maybeeitherheatedorcooledorchangeitsplaceorincrease。But
　　thisisimpossible；forchangeisnotasubject。Or2someother
　　subjectmightchangefromchangeintosomeotherformofexistence
　　e。g。amanfromdiseaseintohealth。Butthisalsoisnotpossible
　　exceptincidentally。Foreverymovementischangefromsomething
　　intosomething。Andsoaregenerationanddestruction；only，these
　　arechangesintothingsopposedincertainwayswhiletheother，
　　movement，isintothingsopposedinanotherway。Athingchanges，
　　then，atthesametimefromhealthintoillness，andfromthis
　　changeitselfintoanother。Clearly，then，ifithasbecomeill，it
　　willhavechangedintowhatevermaybetheotherchangeconcerned
　　thoughitmaybeatrest，and，further，intoadeterminatechange
　　eachtime；andthatnewchangewillbefromsomethingdefiniteinto
　　someotherdefinitething；thereforeitwillbetheoppositechange，
　　thatofgrowingwell。Weanswerthatthishappensonlyincidentally；
　　e。g。thereisachangefromtheprocessofrecollectiontothatof
　　forgetting，onlybecausethattowhichtheprocessattachesis
　　changing，nowintoastateofknowledge，nowintooneofignorance。
　　Further，theprocesswillgoontoinfinity，ifthereistobe
　　changeofchangeandcomingtobeofcomingtobe。Whatistrueofthe
　　later，then，mustbetrueoftheearlier；e。g。ifthesimplecomingto
　　bewasoncecomingtobe，thatwhichcomestobesomethingwasalso
　　oncecomingtobe；thereforethatwhichsimplycomestobesomething
　　wasnotyetinexistence，butsomethingwhichwascomingtobe
　　comingtobesomethingwasalreadyinexistence。Andthiswasonce
　　comingtobe，sothatatthattimeitwasnotyetcomingtobe
　　somethingelse。Nowsinceofaninfinitenumberoftermsthereis
　　notafirst，thefirstinthisserieswillnotexist，andthereforeno
　　followingtermexist。Nothing，then，caneithercometermwitobe
　　ormoveorchange。Further，thatwhichiscapableofamovementis
　　alsocapableofthecontrarymovementandrest，andthatwhichcomes
　　tobealsoceasestobe。Thereforethatwhichiscomingtobeis
　　ceasingtobewhenithascometobecomingtobe；foritcannotcease
　　tobeassoonasitiscomingtobecomingtobe，norafterithas
　　cometobe；forthatwhichisceasingtobemustbe。Further，there
　　mustbeamatterunderlyingthatwhichcomestobeandchanges。What
　　willthisbe，then，-whatisitthatbecomesmovementorbecoming，as
　　bodyorsoulisthatwhichsuffersalteration？And；again，whatis
　　itthattheymoveinto？Foritmustbethemovementorbecomingof
　　somethingfromsomethingintosomething。How，then，canthiscondition
　　befulfilled？Therecanbenolearningoflearning，andthereforeno
　　becomingofbecoming。Sincethereisnotmovementeitherof
　　substanceorofrelationorofactivityandpassivity，itremainsthat
　　movementisinrespectofqualityandquantityandplace；foreach
　　oftheseadmitsofcontrariety。ByqualityImeannotthatwhichisin
　　thesubstanceforeventhedifferentiaisaquality，butthepassive
　　quality，invirtueofwhichathingissaidtobeactedonortobe
　　incapableofbeingactedon。Theimmobileiseitherthatwhichis
　　whollyincapableofbeingmoved，orthatwhichismovedwith
　　difficultyinalongtimeorbeginsslowly，orthatwhichisofa
　　naturetobemovedandcanbemovedbutisnotmovedwhenandwhere
　　andasitwouldnaturallybemoved。ThisaloneamongimmobilesI
　　describeasbeingatrest；forrestiscontrarytomovement，sothat
　　itmustbeaprivationinthatwhichisreceptiveofmovement。
　　Thingswhichareinoneproximateplacearetogetherinplace，and
　　thingswhichareindifferentplacesareapart:thingswhose
　　extremesaretogethertouch:thatatwhichachangingthing，ifit
　　changescontinuouslyaccordingtoitsnature，naturallyarrivesbefore
　　itarrivesattheextremeintowhichitischanging，isbetween。
　　Thatwhichismostdistantinastraightlineiscontraryinplace。
　　Thatissuccessivewhichisafterthebeginningtheorderbeing
　　determinedbypositionorformorinsomeotherwayandhasnothing
　　ofthesameclassbetweenitandthatwhichitsucceeds，e。g。linesin
　　thecaseofaline，unitsinthatofaunit，orahouseinthatofa
　　house。Thereisnothingtopreventathingofsomeotherclassfrom
　　beingbetween。Forthesuccessivesucceedssomethingandissomething
　　later；’one’doesnotsucceed’two’，northefirstdayofthemonth
　　thesecond。Thatwhich，beingsuccessive，touches，iscontiguous。
　　Sinceallchangeisbetweenopposites，andtheseareeither
　　contrariesorcontradictories，andthereisnomiddletermfor
　　contradictories，clearlythatwhichisbetweenisbetweencontraries。
　　Thecontinuousisaspeciesofthecontiguous。Icalltwothings
　　continuouswhenthelimitsofeach，withwhichtheytouchandbywhich
　　theyarekepttogether，becomeoneandthesame，sothatplainlythe
　　continuousisfoundinthethingsoutofwhichaunitynaturally
　　arisesinvirtueoftheircontact。Andplainlythesuccessiveisthe
　　firstoftheseconceptsforthesuccessivedoesnotnecessarily
　　touch，butthatwhichtouchesissuccessive；andifathingis
　　continuous，ittouches，butifittouches，itisnotnecessarily
　　continuous；andinthingsinwhichthereisnotouching，thereisno
　　organicunity；thereforeapointisnotthesameasaunit；for
　　contactbelongstopoints，butnottounits，whichhaveonly
　　succession；andthereissomethingbetweentwooftheformer，but
　　notbetweentwoofthelatter。
　　Thesubjectofourinquiryissubstance；fortheprinciplesand
　　thecausesweareseekingarethoseofsubstances。Foriftheuniverse
　　isofthenatureofawhole，substanceisitsfirstpart；andifit
　　coheresmerelybyvirtueofserialsuccession，onthisviewalso
　　substanceisfirst，andissucceededbyquality，andthenbyquantity。
　　Atthesametimetheselatterarenotevenbeinginthefullsense，
　　butarequalitiesandmovementsofit，-orelseeventhenot-white
　　andthenot-straightwouldbebeing；atleastwesayeventheseare，
　　e。g。’thereisanot-white’。Further，noneofthecategoriesother
　　thansubstancecanexistapart。Andtheearlyphilosophersalsoin
　　practicetestifytotheprimacyofsubstance；foritwasof
　　substancethattheysoughttheprinciplesandelementsandcauses。The
　　thinkersofthepresentdaytendtorankuniversalsassubstancesfor
　　generaareuniversals，andthesetheytendtodescribeasprinciples
　　andsubstances，owingtotheabstractnatureoftheirinquiry；but
　　thethinkersofoldrankedparticularthingsassubstances，e。g。
　　fireandearth，notwhatiscommontoboth，body。
　　Therearethreekindsofsubstance-onethatissensibleof
　　whichonesubdivisioniseternalandanotherisperishable；thelatter
　　isrecognizedbyallmen，andincludese。g。plantsandanimals，of
　　whichwemustgrasptheelements，whetheroneormany；andanother
　　thatisimmovable，andthiscertainthinkersasserttobecapableof
　　existingapart，somedividingitintotwo，othersidentifyingthe
　　Formsandtheobjectsofmathematics，andotherspositing，ofthese
　　two，onlytheobjectsofmathematics。Theformertwokindsof
　　substancearethesubjectofphysicsfortheyimplymovement；but
　　thethirdkindbelongstoanotherscience，ifthereisnoprinciple
　　commontoitandtotheotherkinds。