Asallpotenciesareeitherinnate，likethesenses，orcomeby
　　practice，likethepowerofplayingtheflute，orbylearning，like
　　artisticpower，thosewhichcomebypracticeorbyrationalformulawe
　　mustacquirebypreviousexercisebutthisisnotnecessarywiththose
　　whicharenotofthisnatureandwhichimplypassivity。
　　Sincethatwhichis’capable’iscapableofsomethingandat
　　sometimeinsomewaywithalltheotherqualificationswhichmustbe
　　presentinthedefinition，andsincesomethingscanproducechange
　　accordingtoarationalformulaandtheirpotenciesinvolvesucha
　　formula，whileotherthingsarenonrationalandtheirpotenciesare
　　non-rational，andtheformerpotenciesmustbeinalivingthing，
　　whilethelattercanbebothinthelivingandinthelifeless；as
　　regardspotenciesofthelatterkind，whentheagentandthepatient
　　meetinthewayappropriatetothepotencyinquestion，theonemust
　　actandtheotherbeactedon，butwiththeformerkindofpotency
　　thisisnotnecessary。Forthenonrationalpotenciesareall
　　productiveofoneeffecteach，buttherationalproducecontrary
　　effects，sothatiftheyproducedtheireffectsnecessarilytheywould
　　producecontraryeffectsatthesametime；butthisisimpossible。
　　Theremust，then，besomethingelsethatdecides；Imeanbythis，
　　desireorwill。Forwhicheveroftwothingstheanimaldesires
　　decisively，itwilldo，whenitispresent，andmeetsthepassive
　　object，inthewayappropriatetothepotencyinquestion。Therefore
　　everythingwhichhasarationalpotency，whenitdesiresthatfor
　　whichithasapotencyandinthecircumstancesinwhichithasthe
　　potency，mustdothis。Andithasthepotencyinquestionwhenthe
　　passiveobjectispresentandisinacertainstate；ifnotitwill
　　notbeabletoact。Toaddthequalification’ifnothingexternal
　　preventsit’isnotfurthernecessary；forithasthepotencyonthe
　　termsonwhichthisisapotencyofacting，anditisthisnotin
　　allcircumstancesbutoncertainconditions，amongwhichwillbethe
　　exclusionofexternalhindrances；forthesearebarredbysomeof
　　thepositivequalifications。Andsoevenifonehasarational
　　wish，oranappetite，todotwothingsorcontrarythingsatthe
　　sametime，onewillnotdothem；foritisnotonthesetermsthatone
　　hasthepotencyforthem，norisitapotencyofdoingbothatthe
　　sametime，sinceonewilldothethingswhichitisapotencyof
　　doing，onthetermsonwhichonehasthepotency。
　　Sincewehavetreatedofthekindofpotencywhichisrelatedto
　　movement，letusdiscussactuality-what，andwhatkindofthing，
　　actualityis。Forinthecourseofouranalysisitwillalsobecome
　　clear，withregardtothepotential，thatwenotonlyascribe
　　potencytothatwhosenatureitistomovesomethingelse，ortobe
　　movedbysomethingelse，eitherwithoutqualificationorinsome
　　particularway，butalsousethewordinanothersense，whichisthe
　　reasonoftheinquiryinthecourseofwhichwehavediscussedthese
　　previoussensesalso。Actuality，then，istheexistenceofathingnot
　　inthewaywhichweexpressby’potentially’；wesaythatpotentially，
　　forinstance，astatueofHermesisintheblockofwoodandthe
　　half-lineisinthewhole，becauseitmightbeseparatedout，andwe
　　calleventhemanwhoisnotstudyingamanofscience，ifheis
　　capableofstudying；thethingthatstandsincontrasttoeachof
　　theseexistsactually。Ourmeaningcanbeseenintheparticularcases
　　byinduction，andwemustnotseekadefinitionofeverythingbutbe
　　contenttograsptheanalogy，thatitisasthatwhichisbuilding
　　istothatwhichiscapableofbuilding，andthewakingtothe
　　sleeping，andthatwhichisseeingtothatwhichhasitseyesshutbut
　　hassight，andthatwhichhasbeenshapedoutofthemattertothe
　　matter，andthatwhichhasbeenwroughtuptotheunwrought。Let
　　actualitybedefinedbyonememberofthisantithesis，andthe
　　potentialbytheother。Butallthingsarenotsaidinthesame
　　sensetoexistactually，butonlybyanalogy-asAisinBortoB，C
　　isinDortoD；forsomeareasmovementtopotency，andtheothers
　　assubstancetosomesortofmatter。
　　Butalsotheinfiniteandthevoidandallsimilarthingsaresaid
　　toexistpotentiallyandactuallyinadifferentsensefromthatwhich
　　appliestomanyotherthings，e。g。tothatwhichseesorwalksoris
　　seen。Forofthelatterclassthesepredicatescanatsometimebe
　　alsotrulyassertedwithoutqualification；fortheseenissocalled
　　sometimesbecauseitisbeingseen，sometimesbecauseitiscapableof
　　beingseen。Buttheinfinitedoesnotexistpotentiallyinthesense
　　thatitwilleveractuallyhaveseparateexistence；itexists
　　potentiallyonlyforknowledge。Forthefactthattheprocessof
　　dividingnevercomestoanendensuresthatthisactivityexists
　　potentially，butnotthattheinfiniteexistsseparately。
　　Sinceoftheactionswhichhavealimitnoneisanendbutallare
　　relativetotheend，e。g。theremovingoffat，orfat-removal，andthe
　　bodilypartsthemselveswhenoneismakingthemthinareinmovement
　　inthiswayi。e。withoutbeingalreadythatatwhichthemovement
　　aims，thisisnotanactionoratleastnotacompleteoneforitis
　　notanend；butthatmovementinwhichtheendispresentisan
　　action。E。g。atthesametimeweareseeingandhaveseen，are
　　understandingandhaveunderstood，arethinkingandhavethought
　　whileitisnottruethatatthesametimewearelearningandhave
　　learnt，orarebeingcuredandhavebeencured。Atthesametimewe
　　arelivingwellandhavelivedwell，andarehappyandhavebeen
　　happy。Ifnot，theprocesswouldhavehadsometimetocease，asthe
　　processofmakingthinceases:but，asthingsare，itdoesnot
　　cease；wearelivingandhavelived。Oftheseprocesses，then，wemust
　　calltheonesetmovements，andtheotheractualities。Forevery
　　movementisincomplete-makingthin，learning，walking，building；these
　　aremovements，andincompleteatthat。Foritisnottruethatat
　　thesametimeathingiswalkingandhaswalked，orisbuildingand
　　hasbuilt，oriscomingtobeandhascometobe，orisbeingmoved
　　andhasbeenmoved，butwhatisbeingmovedisdifferentfromwhathas
　　beenmoved，andwhatismovingfromwhathasmoved。Butitisthesame
　　thingthatatthesametimehasseenandisseeing，seeing，oris
　　thinkingandhasthought。Thelattersortofprocess，then，Icall
　　anactuality，andtheformeramovement。
　　What，andwhatkindofthing，theactualis，maybetakenas
　　explainedbytheseandsimilarconsiderations。Butwemustdistinguish
　　whenathingexistspotentiallyandwhenitdoesnot；foritisnotat
　　anyandeverytime。E。g。isearthpotentiallyaman？No-butrather
　　whenithasalreadybecomeseed，andperhapsnoteventhen。Itisjust
　　asitiswithbeinghealed；noteverythingcanbehealedbythe
　　medicalartorbyluck，butthereisacertainkindofthingwhich
　　iscapableofit，andonlythisispotentiallyhealthy。And1the
　　delimitingmarkofthatwhichasaresultofthoughtcomestoexistin
　　completerealityfromhavingexistedpotentiallyisthatifthe
　　agenthaswilledititcomestopassifnothingexternalhinders，
　　whiletheconditionontheotherside-viz。inthatwhichis
　　healed-isthatnothinginithinderstheresult。Itisonsimilar
　　termsthatwehavewhatispotentiallyahouse；ifnothinginthe
　　thingactedon-i。e。inthematter-preventsitfrombecomingahouse，
　　andifthereisnothingwhichmustbeaddedortakenawayor
　　changed，thisispotentiallyahouse；andthesameistrueofall
　　otherthingsthesourceofwhosebecomingisexternal。And2in
　　thecasesinwhichthesourceofthebecomingisintheverything
　　whichcomestobe，athingispotentiallyallthosethingswhichit
　　willbeofitselfifnothingexternalhindersit。E。g。theseedisnot
　　yetpotentiallyaman；foritmustbedepositedinsomethingother
　　thanitselfandundergoachange。Butwhenthroughitsownmotive
　　principleithasalreadygotsuchandsuchattributes，inthisstate
　　itisalreadypotentiallyaman；whileintheformerstateitneeds
　　anothermotiveprinciple，justasearthisnotyetpotentiallya
　　statueforitmustfirstchangeinordertobecomebrass。
　　Itseemsthatwhenwecallathingnotsomethingelsebut
　　’thaten’-e。g。acasketisnot’wood’but’wooden’，andwoodisnot
　　’earth’but’earthen’，andagainearthwillillustrateourpointifit
　　issimilarlynotsomethingelsebut’thaten’-thatotherthingis
　　alwayspotentiallyinthefullsenseofthatwordthethingwhich
　　comesafteritinthisseries。E。g。acasketisnot’earthen’nor
　　’earth’，but’wooden’；forthisispotentiallyacasketandthisis
　　thematterofacasket，woodingeneralofacasketingeneral，and
　　thisparticularwoodofthisparticularcasket。Andifthereisa
　　firstthing，whichisnolonger，inreferencetosomethingelse，
　　called’thaten’，thisisprimematter；e。g。ifearthis’airy’andair
　　isnot’fire’but’fiery’，fireisprimematter，whichisnota
　　’this’。Forthesubjectorsubstratumisdifferentiatedbybeinga
　　’this’ornotbeingone；i。e。thesubstratumofmodificationsis，e。g。
　　aman，i。e。abodyandasoul，whilethemodificationis’musical’
　　or’pale’。Thesubjectiscalled，whenmusiccomestobepresentin
　　it，not’music’but’musical’，andthemanisnot’paleness’but
　　’pale’，andnot’ambulation’or’movement’but’walking’or
　　’moving’，-whichisakintothe’thaten’。Whereverthisisso，then，
　　theultimatesubjectisasubstance；butwhenthisisnotsobutthe
　　predicateisaformanda’this’，theultimatesubjectismatterand
　　materialsubstance。Anditisonlyrightthat’thaten’shouldbe
　　usedwithreferencebothtothematterandtotheaccidents；for
　　bothareindeterminates。
　　Wehavestated，then，whenathingistobesaidtoexist
　　potentiallyandwhenitisnot。
　　Fromourdiscussionofthevarioussensesof’prior’，itis
　　clearthatactualityispriortopotency。AndImeanbypotencynot
　　onlythatdefinitekindwhichissaidtobeaprincipleofchangein
　　anotherthingorinthethingitselfregardedasother，butingeneral
　　everyprincipleofmovementorofrest。Fornaturealsoisinthesame
　　genusaspotency；foritisaprincipleofmovement-not，however，in
　　somethingelsebutinthethingitselfquaitself。Toallsuch
　　potency，then，actualityispriorbothinformulaandin
　　substantiality；andintimeitispriorinonesense，andinanother
　　not。
　　1Clearlyitispriorinformula；forthatwhichisinthe
　　primarysensepotentialispotentialbecauseitispossibleforit
　　tobecomeactive；e。g。Imeanby’capableofbuilding’thatwhich
　　canbuild，andby’capableofseeing’thatwhichcansee，andby
　　’visible’thatwhichcanbeseen。Andthesameaccountappliesto
　　allothercases，sothattheformulaandtheknowledgeoftheonemust
　　precedetheknowledgeoftheother。
　　2Intimeitispriorinthissense:theactualwhichis
　　identicalinspeciesthoughnotinnumberwithapotentially
　　existingthingistoit。Imeanthattothisparticularmanwhonow
　　existsactuallyandtothecornandtotheseeingsubjectthematter
　　andtheseedandthatwhichiscapableofseeing，whichare
　　potentiallyamanandcornandseeing，butnotyetactuallyso，are
　　priorintime；butpriorintimetotheseareotheractually
　　existingthings，fromwhichtheywereproduced。Forfromthe
　　potentiallyexistingtheactuallyexistingisalwaysproducedbyan
　　actuallyexistingthing，e。g。manfromman，musicianbymusician；
　　thereisalwaysafirstmover，andthemoveralreadyexists
　　actually。Wehavesaidinouraccountofsubstancethateverything
　　thatisproducedissomethingproducedfromsomethingandby
　　something，andthatthesameinspeciesasit。
　　Thisiswhyitisthoughtimpossibletobeabuilderifonehas
　　builtnothingoraharperifonehasneverplayedtheharp；forhewho
　　learnstoplaytheharplearnstoplayitbyplayingit，andallother
　　learnersdosimilarly。Andthencearosethesophisticalquibble，
　　thatonewhodoesnotpossessasciencewillbedoingthatwhichis
　　theobjectofthescience；forhewhoislearningitdoesnot
　　possessit。Butsince，ofthatwhichiscomingtobe，somepartmust
　　havecometobe，and，ofthatwhich，ingeneral，ischanging，some
　　partmusthavechangedthisisshowninthetreatiseonmovement，he
　　whoislearningmust，itwouldseem，possesssomepartofthescience。
　　Butheretoo，then，itisclearthatactualityisinthissense
　　also，viz。inorderofgenerationandoftime，priortopotency。
　　But3itisalsopriorinsubstantiality；firstly，abecause
　　thethingsthatareposteriorinbecomingarepriorinformandin
　　substantialitye。g。manispriortoboyandhumanbeingtoseed；
　　fortheonealreadyhasitsform，andtheotherhasnot，and
　　becauseeverythingthatcomestobemovestowardsaprinciple，i。e。an
　　endforthatforthesakeofwhichathingis，isitsprinciple，
　　andthebecomingisforthesakeoftheend，andtheactualityisthe
　　end，anditisforthesakeofthisthatthepotencyisacquired。
　　Foranimalsdonotseeinorderthattheymayhavesight，butthey