Sincetherewerethreekindsofsubstance，twoofthemphysical
andoneunmovable，regardingthelatterwemustassertthatitis
necessarythatthereshouldbeaneternalunmovablesubstance。For
substancesarethefirstofexistingthings，andiftheyareall
destructible，allthingsaredestructible。Butitisimpossiblethat
movementshouldeitherhavecomeintobeingorceasetobeforit
mustalwayshaveexisted，orthattimeshould。Fortherecouldnotbe
abeforeandanafteriftimedidnotexist。Movementalsois
continuous，then，inthesenseinwhichtimeis；fortimeiseither
thesamethingasmovementoranattributeofmovement。Andthereis
nocontinuousmovementexceptmovementinplace，andofthisonlythat
whichiscirculariscontinuous。
Butifthereissomethingwhichiscapableofmovingthingsor
actingonthem，butisnotactuallydoingso，therewillnot
necessarilybemovement；forthatwhichhasapotencyneednot
exerciseit。Nothing，then，isgainedevenifwesupposeeternal
substances，asthebelieversintheFormsdo，unlessthereistobein
themsomeprinciplewhichcancausechange；nay，eventhisisnot
enough，norisanothersubstancebesidestheFormsenough；forifit
isnottoact，therewillbenomovement。Furtherevenifitacts，
thiswillnotbeenough，ifitsessenceispotency；fortherewillnot
beeternalmovement，sincethatwhichispotentiallymaypossibly
notbe。Theremust，then，besuchaprinciple，whoseveryessenceis
actuality。Further，then，thesesubstancesmustbewithoutmatter；for
theymustbeeternal，ifanythingiseternal。Thereforetheymustbe
actuality。
Yetthereisadifficulty；foritisthoughtthateverything
thatactsisabletoact，butthatnoteverythingthatisableto
actacts，sothatthepotencyisprior。Butifthisisso，nothing
thatisneedbe；foritispossibleforallthingstobecapableof
existingbutnotyettoexist。
Yetifwefollowthetheologianswhogeneratetheworldfrom
night，orthenaturalphilosopherswhosaythat’allthingswere
together’，thesameimpossibleresultensues。Forhowwilltherebe
movement，ifthereisnoactuallyexistingcause？Woodwillsurelynot
moveitself-thecarpenter’sartmustactonit；norwillthemenstrual
bloodnortheearthsetthemselvesinmotion，buttheseedsmustact
ontheearthandthesemenonthemenstrualblood。
Thisiswhysomesupposeeternalactuality-e。g。Leucippusand
Plato；fortheysaythereisalwaysmovement。Butwhyandwhatthis
movementistheydosay，nor，iftheworldmovesinthiswayor
that，dotheytellusthecauseofitsdoingso。Nownothingis
movedatrandom，buttheremustalwaysbesomethingpresenttomove
it；e。g。asamatteroffactathingmovesinonewaybynature，and
inanotherbyforceorthroughtheinfluenceofreasonorsomething
else。Further，whatsortofmovementisprimary？Thismakesavast
difference。ButagainforPlato，atleast，itisnotpermissibleto
nameherethatwhichhesometimessupposestobethesourceof
movement-thatwhichmovesitself；forthesoulislater，andcoeval
withtheheavens，accordingtohisaccount。Tosupposepotencyprior
toactuality，then，isinasenseright，andinasensenot；andwe
havespecifiedthesesenses。Thatactualityisprioristestifiedby
Anaxagorasforhis’reason’isactualityandbyEmpedoclesinhis
doctrineofloveandstrife，andbythosewhosaythatthereisalways
movement，e。g。Leucippus。Thereforechaosornightdidnotexistfor
aninfinitetime，butthesamethingshavealwaysexistedeither
passingthroughacycleofchangesorobeyingsomeotherlaw，since
actualityispriortopotency。If，then，thereisaconstantcycle，
somethingmustalwaysremain，actinginthesameway。Andifthere
istobegenerationanddestruction，theremustbesomethingelse
whichisalwaysactingindifferentways。Thismust，then，actin
onewayinvirtueofitself，andinanotherinvirtueofsomething
else-eitherofathirdagent，therefore，orofthefirst。Nowit
mustbeinvirtueofthefirst。Forotherwisethisagaincausesthe
motionbothofthesecondagentandofthethird。Thereforeitis
bettertosay’thefirst’。Foritwasthecauseofeternaluniformity；
andsomethingelseisthecauseofvariety，andevidentlyboth
togetherarethecauseofeternalvariety。This，accordingly，isthe
characterwhichthemotionsactuallyexhibit。Whatneedthenis
theretoseekforotherprinciples？
Since1thisisapossibleaccountofthematter，and2if
itwerenottrue，theworldwouldhaveproceededoutofnightand’all
thingstogether’andoutofnon-being，thesedifficultiesmaybetaken
assolved。Thereis，then，somethingwhichisalwaysmovedwithan
unceasingmotion，whichismotioninacircle；andthisisplainnot
intheoryonlybutinfact。Thereforethefirstheavenmustbe
eternal。Thereisthereforealsosomethingwhichmovesit。Andsince
thatwhichmovesandismovedisintermediate，thereissomething
whichmoveswithoutbeingmoved，beingeternal，substance，and
actuality。Andtheobjectofdesireandtheobjectofthoughtmove
inthisway；theymovewithoutbeingmoved。Theprimaryobjectsof
desireandofthoughtarethesame。Fortheapparentgoodisthe
objectofappetite，andtherealgoodistheprimaryobjectof
rationalwish。Butdesireisconsequentonopinionratherthanopinion
ondesire；forthethinkingisthestarting-point。Andthoughtis
movedbytheobjectofthought，andoneofthetwocolumnsof
oppositesisinitselftheobjectofthought；andinthis，substance
isfirst，andinsubstance，thatwhichissimpleandexists
actually。Theoneandthesimplearenotthesame；for’one’means
ameasure，but’simple’meansthatthethingitselfhasacertain
nature。Butthebeautiful，also，andthatwhichisinitself
desirableareinthesamecolumn；andthefirstinanyclassisalways
best，oranalogoustothebest。
Thatafinalcausemayexistamongunchangeableentitiesis
shownbythedistinctionofitsmeanings。Forthefinalcauseisa
somebeingforwhosegoodanactionisdone，andbsomethingat
whichtheactionaims；andofthesethelatterexistsamong
unchangeableentitiesthoughtheformerdoesnot。Thefinalcause，
then，producesmotionasbeingloved，butallotherthingsmoveby
beingmoved。Nowifsomethingismoveditiscapableofbeing
otherwisethanasitis。Thereforeifitsactualityistheprimary
formofspatialmotion，theninsofarasitissubjecttochange，
inthisrespectitiscapableofbeingotherwise，-inplace，evenif
notinsubstance。Butsincethereissomethingwhichmoveswhile
itselfunmoved，existingactually，thiscaninnowaybeotherwise
thanasitis。Formotioninspaceisthefirstofthekindsof
change，andmotioninacirclethefirstkindofspatialmotion；and
thisthefirstmoverproduces。Thefirstmover，then，existsof
necessity；andinsofarasitexistsbynecessity，itsmodeof
beingisgood，anditisinthissenseafirstprinciple。Forthe
necessaryhasallthesesenses-thatwhichisnecessaryperforce
becauseitiscontrarytothenaturalimpulse，thatwithoutwhich
thegoodisimpossible，andthatwhichcannotbeotherwisebutcan
existonlyinasingleway。
Onsuchaprinciple，then，dependtheheavensandtheworldof
nature。Anditisalifesuchasthebestwhichweenjoy，andenjoy
forbutashorttimeforitiseverinthisstate，whichwecannot
be，sinceitsactualityisalsopleasure。Andforthisreasonare
waking，perception，andthinkingmostpleasant，andhopesandmemories
aresoonaccountofthese。Andthinkinginitselfdealswiththat
whichisbestinitself，andthatwhichisthinkinginthefullest
sensewiththatwhichisbestinthefullestsense。Andthoughtthinks
onitselfbecauseitsharesthenatureoftheobjectofthought；for
itbecomesanobjectofthoughtincomingintocontactwithand
thinkingitsobjects，sothatthoughtandobjectofthoughtarethe
same。Forthatwhichiscapableofreceivingtheobjectofthought，
i。e。theessence，isthought。Butitisactivewhenitpossesses
thisobject。Thereforethepossessionratherthanthereceptivityis
thedivineelementwhichthoughtseemstocontain，andtheactof
contemplationiswhatismostpleasantandbest。If，then，Godis
alwaysinthatgoodstateinwhichwesometimesare，thiscompels
ourwonder；andifinabetterthiscompelsityetmore。AndGodisin
abetterstate。AndlifealsobelongstoGod；fortheactualityof
thoughtislife，andGodisthatactuality；andGod’sself-dependent
actualityislifemostgoodandeternal。WesaythereforethatGod
isalivingbeing，eternal，mostgood，sothatlifeandduration
continuousandeternalbelongtoGod；forthisisGod。
Thosewhosuppose，asthePythagoreansandSpeusippusdo，that
supremebeautyandgoodnessarenotpresentinthebeginning，
becausethebeginningsbothofplantsandofanimalsarecauses，but
beautyandcompletenessareintheeffectsofthese，arewrongin
theiropinion。Fortheseedcomesfromotherindividualswhichare
priorandcomplete，andthefirstthingisnotseedbutthecomplete
being；e。g。wemustsaythatbeforetheseedthereisaman，-notthe
manproducedfromtheseed，butanotherfromwhomtheseedcomes。
Itisclearthenfromwhathasbeensaidthatthereisasubstance
whichiseternalandunmovableandseparatefromsensiblethings。It
hasbeenshownalsothatthissubstancecannothaveanymagnitude，but
iswithoutpartsandindivisibleforitproducesmovementthrough
infinitetime，butnothingfinitehasinfinitepower；and，whileevery
magnitudeiseitherinfiniteorfinite，itcannot，fortheabove
reason，havefinitemagnitude，anditcannothaveinfinitemagnitude
becausethereisnoinfinitemagnitudeatall。Butithasalsobeen
shownthatitisimpassiveandunalterable；foralltheother
changesareposteriortochangeofplace。
Itisclear，then，whythesethingsareastheyare。Butwemust
notignorethequestionwhetherwehavetosupposeonesuch
substanceormorethanone，andifthelatter，howmany；wemust
alsomention，regardingtheopinionsexpressedbyothers，thatthey
havesaidnothingaboutthenumberofthesubstancesthatcaneven
beclearlystated。ForthetheoryofIdeashasnospecialdiscussion
ofthesubject；forthosewhospeakofIdeassaytheIdeasare
numbers，andtheyspeakofnumbersnowasunlimited，nowaslimitedby
thenumber10；butasforthereasonwhythereshouldbejustso
manynumbers，nothingissaidwithanydemonstrativeexactness。We
howevermustdiscussthesubject，startingfromthepresuppositions
anddistinctionswehavementioned。Thefirstprincipleorprimary
beingisnotmovableeitherinitselforaccidentally，butproduces
theprimaryeternalandsinglemovement。Butsincethatwhichismoved
mustbemovedbysomething，andthefirstmovermustbeinitself
unmovable，andeternalmovementmustbeproducedbysomething
eternalandasinglemovementbyasinglething，andsinceweseethat
besidesthesimplespatialmovementoftheuniverse，whichwesay
thefirstandunmovablesubstanceproduces，thereareotherspatial
movements-thoseoftheplanets-whichareeternalforabodywhich
movesinacircleiseternalandunresting；wehaveprovedthese
pointsinthephysicaltreatises，eachofthesemovementsalsomust
becausedbyasubstancebothunmovableinitselfandeternal。Forthe
natureofthestarsiseternaljustbecauseitisacertainkindof
substance，andthemoveriseternalandpriortothemoved，andthat
whichispriortoasubstancemustbeasubstance。Evidently，then，
theremustbesubstanceswhichareofthesamenumberasthemovements
ofthestars，andintheirnatureeternal，andinthemselves
unmovable，andwithoutmagnitude，forthereasonbeforementioned。
Thatthemoversaresubstances，then，andthatoneoftheseisfirst
andanothersecondaccordingtothesameorderasthemovementsofthe
stars，isevident。Butinthenumberofthemovementswereacha
problemwhichmustbetreatedfromthestandpointofthatoneofthe
mathematicalscienceswhichismostakintophilosophy-viz。of
astronomy；forthissciencespeculatesaboutsubstancewhichis
perceptiblebuteternal，buttheothermathematicalsciences，i。e。
arithmeticandgeometry，treatofnosubstance。Thatthemovementsare
morenumerousthanthebodiesthataremovedisevidenttothosewho
havegivenevenmoderateattentiontothematter；foreachofthe
planetshasmorethanonemovement。Butastotheactualnumberof
thesemovements，wenow-togivesomenotionofthesubject-quote
whatsomeofthemathematicianssay，thatourthoughtmayhavesome
definitenumbertograsp；but，fortherest，wemustpartly
investigateforourselves，Partlylearnfromotherinvestigators，
andifthosewhostudythissubjectformanopinioncontrarytowhat
wehavenowstated，wemustesteembothpartiesindeed，butfollowthe
moreaccurate。