Orhas’definition’，like’whatathingis’，severalmeanings？
’Whatathingis’inonesensemeanssubstanceandthe’this’，in
anotheroneorotherofthepredicates，quantity，quality，andthe
like。Foras’is’belongstoallthings，nothoweverinthesame
sense，buttoonesortofthingprimarilyandtoothersinasecondary
way，sotoo’whatathingis’belongsinthesimplesenseto
substance，butinalimitedsensetotheothercategories。Forevenof
aqualitywemightaskwhatitis，sothatqualityalsoisa’whata
thingis’，-notinthesimplesense，however，butjustas，inthe
caseofthatwhichisnot，somesay，emphasizingthelinguistic
form，thatthatiswhichisnotis-notissimply，butisnon-existent；
sotoowithquality。
Wemustnodoubtinquirehowweshouldexpressourselvesoneach
point，butcertainlynotmorethanhowthefactsactuallystand。And
sonowalso，sinceitisevidentwhatlanguageweuse，essencewill
belong，justas’whatathingis’does，primarilyandinthesimple
sensetosubstance，andinasecondarywaytotheothercategories
also，-notessenceinthesimplesense，buttheessenceofaqualityor
ofaquantity。Foritmustbeeitherbyanequivocationthatwesay
theseare，orbyaddingtoandtakingfromthemeaningof’are’in
thewayinwhichthatwhichisnotknownmaybesaidtobeknown，-the
truthbeingthatweusethewordneitherambiguouslynorinthesame
sense，butjustasweapplytheword’medical’byvirtueofa
referencetooneandthesamething，notmeaningoneandthesame
thing，noryetspeakingambiguously；forapatientandanoperation
andaninstrumentarecalledmedicalneitherbyanambiguitynor
withasinglemeaning，butwithreferencetoacommonend。Butitdoes
notmatteratallinwhichofthetwowaysonelikestodescribethe
facts；thisisevident，thatdefinitionandessenceintheprimaryand
simplesensebelongtosubstances。Stilltheybelongtootherthings
aswell，onlynotintheprimarysense。Forifwesupposethisitdoes
notfollowthatthereisadefinitionofeverywordwhichmeansthe
sameasanyformula；itmustmeanthesameasaparticularkindof
formula；andthisconditionissatisfiedifitisaformulaof
somethingwhichisone，notbycontinuityliketheIliadorthethings
thatareonebybeingboundtogether，butinoneofthemainsensesof
’one’，whichanswertothesensesof’is’；now’thatwhichis’in
onesensedenotesa’this’，inanotheraquantity，inanothera
quality。Andsotherecanbeaformulaordefinitionevenofwhite
man，butnotinthesenseinwhichthereisadefinitioneitherof
whiteorofasubstance。
Itisadifficultquestion，ifonedeniesthataformulawithan
addeddeterminantisadefinition，whetheranyofthetermsthatare
notsimplebutcoupledwillbedefinable。Forwemustexplainthem
byaddingadeterminant。E。g。thereisthenose，andconcavity，and
snubness，whichiscompoundedoutofthetwobythepresenceofthe
oneintheother，anditisnotbyaccidentthatthenosehasthe
attributeeitherofconcavityorofsnubness，butinvirtueofits
nature；nordotheyattachtoitaswhitenessdoestoCallias，orto
manbecauseCallias，whohappenstobeaman，iswhite，butas
’male’attachestoanimaland’equal’toquantity，andasall
so-called’attributespropterse’attachtotheirsubjects。Andsuch
attributesarethoseinwhichisinvolvedeithertheformulaorthe
nameofthesubjectoftheparticularattribute，andwhichcannotbe
explainedwithoutthis；e。g。whitecanbeexplainedapartfromman，
butnotfemaleapartfromanimal。Thereforethereiseithernoessence
anddefinitionofanyofthesethings，orifthereis，itisin
anothersense，aswehavesaid。
Butthereisalsoaseconddifficultyaboutthem。Forifsnubnose
andconcavenosearethesamething，snubandconcavewillbethe
thing；butifsnubandconcavearenotthesamebecauseitis
impossibletospeakofsnubnessapartfromthethingofwhichitisan
attributepropterse，forsnubnessisconcavity-in-a-nose，either
itisimpossibletosay’snubnose’orthesamethingwillhavebeen
saidtwice，concave-nosenose；forsnubnosewillbeconcave-nose
nose。Andsoitisabsurdthatsuchthingsshouldhaveanessence；
iftheyhave，therewillbeaninfiniteregress；forinsnub-nosenose
yetanother’nose’willbeinvolved。
Clearly，then，onlysubstanceisdefinable。Foriftheother
categoriesalsoaredefinable，itmustbebyadditionofa
determinant，e。g。thequalitativeisdefinedthus，andsoisthe
odd，foritcannotbedefinedapartfromnumber；norcanfemalebe
definedapartfromanimal。WhenIsay’byaddition’Imeanthe
expressionsinwhichitturnsoutthatwearesayingthesamething
twice，asintheseinstances。Andifthisistrue，coupledterms
also，like’oddnumber’，willnotbedefinablebutthisescapesour
noticebecauseourformulaearenotaccurate。。Butifthesealso
aredefinable，eitheritisinsomeotherwayor，aswedefinitionand
essencemustbesaidtohavemorethanonesense。Thereforeinone
sensenothingwillhaveadefinitionandnothingwillhaveanessence，
exceptsubstances，butinanothersenseotherthingswillhavethem。
Clearly，then，definitionistheformulaoftheessence，andessence
belongstosubstanceseitheraloneorchieflyandprimarilyandinthe
unqualifiedsense。
Wemustinquirewhethereachthinganditsessencearethesameor
different。Thisisofsomeusefortheinquiryconcerningsubstance；
foreachthingisthoughttobenotdifferentfromitssubstance，
andtheessenceissaidtobethesubstanceofeachthing。
Nowinthecaseofaccidentalunitiesthetwowouldbegenerally
thoughttobedifferent，e。g。whitemanwouldbethoughttobe
differentfromtheessenceofwhiteman。Foriftheyarethesame，the
essenceofmanandthatofwhitemanarealsothesame；foraman
andawhitemanarethesamething，aspeoplesay，sothattheessence
ofwhitemanandthatofmanwouldbealsothesame。Butperhapsit
doesnotfollowthattheessenceofaccidentalunitiesshouldbethe
sameasthatofthesimpleterms。Fortheextremetermsarenotinthe
samewayidenticalwiththemiddleterm。Butperhapsthismightbe
thoughttofollow，thattheextremeterms，theaccidents，should
turnouttobethesame，e。g。theessenceofwhiteandthatof
musical；butthisisnotactuallythoughttobethecase。
Butinthecaseofso-calledself-subsistentthings，isathing
necessarilythesameasitsessence？E。g。iftherearesomesubstances
whichhavenoothersubstancesnorentitiespriortothem-substances
suchassomeasserttheIdeastobe？-Iftheessenceofgoodistobe
differentfromgood-itself，andtheessenceofanimalfrom
animal-itself，andtheessenceofbeingfrombeing-itself，therewill，
firstly，beothersubstancesandentitiesandIdeasbesidesthose
whichareasserted，and，secondly，theseotherswillbeprior
substances，ifessenceissubstance。Andiftheposteriorsubstances
andthepriorareseveredfromeachother，atherewillbeno
knowledgeoftheformer，andbthelatterwillhavenobeing。By
’severed’Imean，ifthegood-itselfhasnottheessenceofgood，
andthelatterhasnotthepropertyofbeinggood。Forathereis
knowledgeofeachthingonlywhenweknowitsessence。Andbthe
caseisthesameforotherthingsasforthegood；sothatifthe
essenceofgoodisnotgood，neitheristheessenceofrealityreal，
northeessenceofunityone。Andallessencesalikeexistornone
ofthemdoes；sothatiftheessenceofrealityisnotreal，neither
isanyoftheothers。Again，thattowhichtheessenceofgooddoes
notbelongisnotgood-Thegood，then，mustbeonewiththeessence
ofgood，andthebeautifulwiththeessenceofbeauty，andsowithall
thingswhichdonotdependonsomethingelsebutareself-subsistent
andprimary。Foritisenoughiftheyarethis，eveniftheyarenot
Forms；orrather，perhaps，eveniftheyareForms。Atthesametime
itisclearthatifthereareIdeassuchassomepeoplesaythereare，
itwillnotbesubstratumthatissubstance；forthesemustbe
substances，butnotpredicableofasubstratum；foriftheywere
theywouldexistonlybybeingparticipatedin。
Eachthingitself，then，anditsessenceareoneandthesamein
nomerelyaccidentalway，asisevidentbothfromthepreceding
argumentsandbecausetoknoweachthing，atleast，isjusttoknow
itsessence，sothatevenbytheexhibitionofinstancesitbecomes
clearthatbothmustbeone。
Butofanaccidentalterm，e。g。’themusical’or’thewhite’，
sinceithastwomeanings，itisnottruetosaythatititselfis
identicalwithitsessence；forboththattowhichtheaccidental
qualitybelongs，andtheaccidentalquality，arewhite，sothatina
sensetheaccidentanditsessencearethesame，andinasensethey
arenot；fortheessenceofwhiteisnotthesameasthemanorthe
whiteman，butitisthesameastheattributewhite。
Theabsurdityoftheseparationwouldappearalsoifonewereto
assignanametoeachoftheessences；fortherewouldbeyet
anotheressencebesidestheoriginalone，e。g。totheessenceofhorse
therewillbelongasecondessence。Yetwhyshouldnotsomethings
betheiressencesfromthestart，sinceessenceissubstance？But
indeednotonlyareathinganditsessenceone，buttheformulaof
themisalsothesame，asisclearevenfromwhathasbeensaid；for
itisnotbyaccidentthattheessenceofone，andtheone，areone。
Further，iftheyaretobedifferent，theprocesswillgoonto
infinity；forweshallhave1theessenceofone，and2theone，
sothattotermsoftheformerkindthesameargumentwillbe
applicable。
Clearly，then，eachprimaryandself-subsistentthingisoneand
thesameasitsessence。Thesophisticalobjectionstothis
position，andthequestionwhetherSocratesandtobeSocratesarethe
samething，areobviouslyansweredbythesamesolution；forthere
isnodifferenceeitherinthestandpointfromwhichthequestion
wouldbeasked，orinthatfromwhichonecouldanswerit
successfully。Wehaveexplained，then，inwhatsenseeachthingisthe
sameasitsessenceandinwhatsenseitisnot。
Ofthingsthatcometobe，somecometobebynature，somebyart，
somespontaneously。Noweverythingthatcomestobecomestobebythe
agencyofsomethingandfromsomethingandcomestobesomething。
AndthesomethingwhichIsayitcomestobemaybefoundinany
category；itmaycometobeeithera’this’orofsomesizeorofsome
qualityorsomewhere。
Nownaturalcomingstobearethecomingstobeofthosethings
whichcometobebynature；andthatoutofwhichtheycometobeis
whatwecallmatter；andthatbywhichtheycometobeissomething
whichexistsnaturally；andthesomethingwhichtheycometobeisa
manoraplantoroneofthethingsofthiskind，whichwesayare
substancesifanythingis-allthingsproducedeitherbynatureorby
arthavematter；foreachofthemiscapablebothofbeingandof
notbeing，andthiscapacityisthematterineach-and，ingeneral，
boththatfromwhichtheyareproducedisnature，andthetype
accordingtowhichtheyareproducedisnatureforthatwhichis
produced，e。g。aplantorananimal，hasanature，andsoisthat
bywhichtheyareproduced——theso-called’formal’nature，whichis
specificallythesamethoughthisisinanotherindividual；for
manbegetsman。