This，then，musteitherbeeternaloritmustbedestructible
　　withoutbeingeverincourseofbeingdestroyed，andmusthavecometo
　　bewithouteverbeingincourseofcomingtobe。Butithasbeen
　　provedandexplainedelsewherethatnoonemakesorbegetstheform，
　　butitistheindividualthatismade，i。e。thecomplexofformand
　　matterthatisgenerated。Whetherthesubstancesofdestructible
　　thingscanexistapart，isnotyetatallclear；exceptthatobviously
　　thisisimpossibleinsomecases-inthecaseofthingswhichcannot
　　existapartfromtheindividualinstances，e。g。houseorutensil。
　　Perhaps，indeed，neitherthesethingsthemselves，noranyoftheother
　　thingswhicharenotformedbynature，aresubstancesatall；for
　　onemightsaythatthenatureinnaturalobjectsistheonlysubstance
　　tobefoundindestructiblethings。
　　Thereforethedifficultywhichusedtoberaisedbytheschool
　　ofAntisthenesandothersuchuneducatedpeoplehasacertain
　　timeliness。Theysaidthatthe’what’cannotbedefinedforthe
　　definitionsocalledisa’longrigmarole’butofwhatsorta
　　thing，e。g。silver，is，theythoughtitpossibleactuallyto
　　explain，notsayingwhatitis，butthatitisliketin。Thereforeone
　　kindofsubstancecanbedefinedandformulated，i。e。thecomposite
　　kind，whetheritbeperceptibleorintelligible；buttheprimaryparts
　　ofwhichthisconsistscannotbedefined，sinceadefinitoryformula
　　predicatessomethingofsomething，andonepartofthedefinitionmust
　　playthepartofmatterandtheotherthatofform。
　　Itisalsoobviousthat，ifsubstancesareinasensenumbers，
　　theyaresointhissenseandnot，assomesay，asnumbersofunits。
　　Foradefinitionisasortofnumber；for1itisdivisible，and
　　intoindivisiblepartsfordefinitoryformulaearenotinfinite，and
　　numberalsoisofthisnature。And2as，whenoneofthepartsof
　　whichanumberconsistshasbeentakenfromoraddedtothenumber，it
　　isnolongerthesamenumber，butadifferentone，evenifitisthe
　　verysmallestpartthathasbeentakenawayoradded，sothe
　　definitionandtheessencewillnolongerremainwhenanythinghas
　　beentakenawayoradded。And3thenumbermustbesomethingin
　　virtueofwhichitisone，andthisthesethinkerscannotstate，
　　whatmakesitone，ifitisoneforeitheritisnotonebutasort
　　ofheap，orifitis，weoughttosaywhatitisthatmakesoneoutof
　　many；andthedefinitionisone，butsimilarlytheycannotsaywhat
　　makesitone。Andthisisanaturalresult；forthesamereasonis
　　applicable，andsubstanceisoneinthesensewhichwehaveexplained，
　　andnot，assomesay，bybeingasortofunitorpoint；eachisa
　　completerealityandadefinitenature。And4asnumberdoesnot
　　admitofthemoreandtheless，neitherdoessubstance，inthesense
　　ofform，butifanysubstancedoes，itisonlythesubstancewhich
　　involvesmatter。Letthis，then，sufficeforanaccountofthe
　　generationanddestructionofso-calledsubstancesinwhatsenseitis
　　possibleandinwhatsenseimpossible——andofthereductionof
　　thingstonumber。
　　Regardingmaterialsubstancewemustnotforgetthatevenifall
　　thingscomefromthesamefirstcauseorhavethesamethingsfor
　　theirfirstcauses，andifthesamematterservesasstarting-point
　　fortheirgeneration，yetthereisamatterpropertoeach，e。g。for
　　phlegmthesweetorthefat，andforbilethebitter，orsomething
　　else；thoughperhapsthesecomefromthesameoriginalmatter。And
　　therecometobeseveralmattersforthesamething，whentheone
　　matterismatterfortheother；e。g。phlegmcomesfromthefatand
　　fromthesweet，ifthefatcomesfromthesweet；anditcomesfrom
　　bilebyanalysisofthebileintoitsultimatematter。Foronething
　　comesfromanotherintwosenses，eitherbecauseitwillbefoundata
　　laterstage，orbecauseitisproducediftheotherisanalysedinto
　　itsoriginalconstituents。Whenthematterisone，differentthings
　　maybeproducedowingtodifferenceinthemovingcause；e。g。from
　　woodmaybemadebothachestandabed。Butsomedifferentthings
　　musthavetheirmatterdifferent；e。g。asawcouldnotbemadeof
　　wood，noristhisinthepowerofthemovingcause；foritcouldnot
　　makeasawofwoolorofwood。Butif，asamatteroffact，thesame
　　thingcanbemadeofdifferentmaterial，clearlytheart，i。e。the
　　movingprinciple，isthesame；forifboththematterandthemoving
　　causeweredifferent，theproductwouldbesotoo。
　　Whenoneinquiresintothecauseofsomething，oneshould，since
　　’causes’arespokenofinseveralsenses，stateallthepossible
　　causes。whatisthematerialcauseofman？Shallwesay’themenstrual
　　fluid’？Whatismovingcause？Shallwesay’theseed’？Theformal
　　cause？Hisessence。Thefinalcause？Hisend。Butperhapsthelatter
　　twoarethesame-Itistheproximatecauseswemuststate。Whatis
　　thematerialcause？Wemustnamenotfireorearth，butthematter
　　peculiartothething。
　　Regardingthesubstancesthatarenaturalandgenerable，ifthe
　　causesarereallytheseandofthisnumberandwehavetolearnthe
　　causes，wemustinquirethus，ifwearetoinquirerightly。Butinthe
　　caseofnaturalbuteternalsubstancesanotheraccountmustbe
　　given。Forperhapssomehavenomatter，ornotmatterofthissortbut
　　onlysuchascanbemovedinrespectofplace。Nordoesmatter
　　belongtothosethingswhichexistbynaturebutarenotsubstances；
　　theirsubstratumisthesubstance。E。gwhatisthecauseofeclipse？
　　Whatisitsmatter？Thereisnone；themoonisthatwhichsuffers
　　eclipse。Whatisthemovingcausewhichextinguishedthelight？The
　　earth。Thefinalcauseperhapsdoesnotexist。Theformalprincipleis
　　thedefinitoryformula，butthisisobscureifitdoesnotincludethe
　　cause。E。g。whatiseclipse？Deprivationoflight。Butifweadd’by
　　theearth’scominginbetween’，thisistheformulawhichincludesthe
　　cause。Inthecaseofsleepitisnotclearwhatitisthat
　　proximatelyhasthisaffection。Shallwesaythatitistheanimal？
　　Yes，buttheanimalinvirtueofwhat，i。e。whatistheproximate
　　subject？Theheartorsomeotherpart。Next，bywhatisitproduced？
　　Next，whatistheaffection-thatoftheproximatesubject，notof
　　thewholeanimal？Shallwesaythatitisimmobilityofsuchand
　　suchakind？Yes，buttowhatprocessintheproximatesubjectisthis
　　due？
　　Sincesomethingsareandarenot，withoutcomingtobeand
　　ceasingtobe，e。g。points，iftheycanbesaidtobe，andin
　　generalformsforitisnot’white’comestobe，butthewoodcomes
　　tobewhite，ifeverythingthatcomestobecomesfromsomethingand
　　comestobesomething，notallcontrariescancomefromone
　　another，butitisindifferentsensesthatapalemancomesfroma
　　darkman，andpalecomesfromdark。Norhaseverythingmatter，but
　　onlythosethingswhichcometobeandchangeintooneanother。
　　Thosethingswhich，withouteverbeingincourseofchanging，areor
　　arenot，havenomatter。
　　Thereisdifficultyinthequestionhowthematterofeachthing
　　isrelatedtoitscontrarystates。E。g。ifthebodyispotentially
　　healthy，anddiseaseiscontrarytohealth，isitpotentiallyboth
　　healthyanddiseased？Andiswaterpotentiallywineandvinegar？We
　　answerthatitisthematterofoneinvirtueofitspositivestate
　　anditsform，andoftheotherinvirtueoftheprivationofits
　　positivestateandthecorruptionofitcontrarytoitsnature。It
　　isalsohardtosaywhywineisnotsaidtobethematterofvinegar
　　norpotentiallyvinegarthoughvinegarisproducedfromit，and
　　whyalivingmanisnotsaidtobepotentiallydead。Infactthey
　　arenot，butthecorruptionsinquestionareaccidental，anditisthe
　　matteroftheanimalthatisitselfinvirtueofitscorruptionthe
　　potencyandmatterofacorpse，anditiswaterthatisthematter
　　ofvinegar。Forthecorpsecomesfromtheanimal，andvinegarfrom
　　wine，asnightfromday。Andallthethingswhichchangethusintoone
　　anothermustgobacktotheirmatter；e。g。iffromacorpseis
　　producedananimal，thecorpsefirstgoesbacktoitsmatter，andonly
　　thenbecomesananimal；andvinegarfirstgoesbacktowater，andonly
　　thenbecomeswine。
　　Toreturntothedifficultywhichhasbeenstatedwithrespect
　　bothtodefinitionsandtonumbers，whatisthecauseoftheir
　　unity？Inthecaseofallthingswhichhaveseveralpartsandinwhich
　　thetotalityisnot，asitwere，amereheap，butthewholeis
　　somethingbesidetheparts，thereisacause；foreveninbodies
　　contactisthecauseofunityinsomecases，andinothersviscosity
　　orsomeothersuchquality。Andadefinitionisasetofwordswhich
　　isonenotbybeingconnectedtogether，liketheIliad，butbydealing
　　withoneobject-Whatthen，isitthatmakesmanone；whyisheone
　　andnotmany，e。g。animalbiped，especiallyifthereare，assome
　　say，ananimal-itselfandabiped-itself？WhyarenotthoseForms
　　themselvestheman，sothatmenwouldexistbyparticipationnotin
　　man，norin-oneForm，butintwo，animalandbiped，andingeneralman
　　wouldbenotonebutmorethanonething，animalandbiped？
　　Clearly，then，ifpeopleproceedthusintheirusualmannerof
　　definitionandspeech，theycannotexplainandsolvethedifficulty。
　　Butif，aswesay，oneelementismatterandanotherisform，and
　　oneispotentiallyandtheotheractually，thequestionwillnolonger
　　bethoughtadifficulty。Forthisdifficultyisthesameaswould
　　ariseif’roundbronze’werethedefinitionof’cloak’；forthis
　　wordwouldbeasignofthedefinitoryformula，sothatthequestion
　　is，whatisthecauseoftheunityof’round’and’bronze’？The
　　difficultydisappears，becausetheoneismatter，theotherform。
　　What，then，causesthis-thatwhichwaspotentiallytobe
　　actually-except，inthecaseofthingswhicharegenerated，theagent？
　　Forthereisnoothercauseofthepotentialsphere’sbecoming
　　actuallyasphere，butthiswastheessenceofeither。Ofmatter
　　someisintelligible，someperceptible，andinaformulathereis
　　alwaysanelementofmatteraswellasoneofactuality；e。g。the
　　circleis’aplanefigure’。Butofthethingswhichhavenomatter，
　　eitherintelligibleorperceptible，eachisbyitsnature
　　essentiallyakindofunity，asitisessentiallyakindof
　　being-individualsubstance，quality，orquantityandsoneither
　　’existent’nor’one’ispresentintheirdefinitions，andtheessence
　　ofeachofthemisbyitsverynatureakindofunityasitisa
　　kindofbeing-andsononeofthesehasanyreasonoutsideitself，
　　forbeingone，norforbeingakindofbeing；foreachisbyits
　　natureakindofbeingandakindofunity，notasbeinginthe
　　genus’being’or’one’norinthesensethatbeingandunitycanexist
　　apartfromparticulars。
　　Owingtothedifficultyaboutunitysomespeakof’participation’，
　　andraisethequestion，whatisthecauseofparticipationandwhatis
　　ittoparticipate；andothersspeakof’communion’，asLycophron
　　saysknowledgeisacommunionofknowingwiththesoul；andotherssay
　　lifeisa’composition’or’connexion’ofsoulwithbody。Yetthesame
　　accountappliestoallcases；forbeinghealthy，too，willonthis
　　showingbeeithera’communion’ora’connexion’ora’composition’of
　　soulandhealth，andthefactthatthebronzeisatrianglewillbe
　　a’composition’ofbronzeandtriangle，andthefactthatathingis
　　whitewillbea’composition’ofsurfaceandwhiteness。Thereason
　　isthatpeoplelookforaunifyingformula，andadifference，
　　betweenpotencyandcompletereality。But，ashasbeensaid，the
　　proximatematterandtheformareoneandthesamething，theone
　　potentially，andtheotheractually。Thereforeitislikeasking
　　whatingeneralisthecauseofunityandofathing’sbeingone；
　　foreachthingisaunity，andthepotentialandtheactualare
　　somehowone。Thereforethereisnoothercausehereunlessthereis
　　somethingwhichcausedthemovementfrompotencyintoactuality。And
　　allthingswhichhavenomatterarewithoutqualification
　　essentiallyunities。