d　it　in　their　fabulous　way　upon　animate　necessity。　We　must　no　more　believe　that　than　follow　Empedocles　when　he　says　that　the　world；　by　being　whirled　round；　received　a　movement　quick　enough　to　overpower　its　own　downward　tendency；　and　thus　has　been　kept　from　destruction　all　this　time。　Nor；　again；　is　it　conceivable　that　it　should　persist　eternally　by　the　necessitation　of　a　soul。　For　a　soul　could　not　live　in　such　conditions　painlessly　or　happily；　since　the　movement　involves　constraint；　being　imposed　on　the　first　body；　whose　natural　motion　is　different；　and　imposed　continuously。　It　must　therefore　be　uneasy　and　devoid　of　all　rational　satisfaction；　for　it　could　not　even；　like　the　soul　of　mortal　animals；　take　recreation　in　the　bodily　relaxation　of　sleep。　An　Ixion's　lot　must　needs　possess　it；　without　end　or　respite。　If　then；　as　we　said；　the　view　already　stated　of　the　first　motion　is　a　possible　one；　it　is　not　only　more　appropriate　so　to　conceive　of　its　eternity；　but　also　on　this　hypothesis　alone　are　we　able　to　advance　a　theory　consistent　with　popular　divinations　of　the　divine　nature。　But　of　this　enough　for　the　present。
  2
  Since　there　are　some　who　say　that　there　is　a　right　and　a　left　in　the　heaven；　with　those　who　are　known　as　Pythagoreans…to　whom　indeed　the　view　really　belongs…we　must　consider　whether；　if　we　are　to　apply　these　principles　to　the　body　of　the　universe；　we　should　follow　their　statement　of　the　matter　or　find　a　better　way。　At　the　start　we　may　say　that；　if　right　and　left　are　applicable；　there　are　prior　principles　which　must　first　be　applied。　These　principles　have　been　analysed　in　the　discussion　of　the　movements　of　animals；　for　the　reason　that　they　are　proper　to　animal　nature。　For　in　some　animals　we　find　all　such　distinctions　of　parts　as　this　of　right　and　left　clearly　present；　and　in　others　some；　but　in　plants　we　find　only　above　and　below。　Now　if　we　are　to　apply　to　the　heaven　such　a　distinction　of　parts；　we　must　exect；　as　we　have　said；　to　find　in　it　also　the　distinction　which　in　animals　is　found　first　of　them　all。　The　distinctions　are　three；　namely；　above　and　below；　front　and　its　opposite；　right　and　left…all　these　three　oppositions　we　expect　to　find　in　the　perfect　body…and　each　may　be　called　a　principle。　Above　is　the　principle　of　length；　right　of　breadth；　front　of　depth。　Or　again　we　may　connect　them　with　the　various　movements；　taking　principle　to　mean　that　part；　in　a　thing　capable　of　movement；　from　which　movement　first　begins。　Growth　starts　from　above；　locomotion　from　the　right；　sensemovement　from　in　front　（for　front　is　simply　the　part　to　which　the　senses　are　directed）。　Hence　we　must　not　look　for　above　and　below；　right　and　left；　front　and　back；　in　every　kind　of　body；　but　only　in　those　which；　being　animate；　have　a　principle　of　movement　within　themselves。　For　in　no　inanimate　thing　do　we　observe　a　part　from　which　movement　originates。　Some　do　not　move　at　all；　some　move；　but　not　indifferently　in　any　direction；　fire；　for　example；　only　upward；　and　earth　only　to　the　centre。　It　is　true　that　we　speak　of　above　and　below；　right　and　left；　in　these　bodies　relatively　to　ourselves。　The　reference　may　be　to　our　own　right　hands；　as　with　the　diviner；　or　to　some　similarity　to　our　own　members；　such　as　the　parts　of　a　statue　possess；　or　we　may　take　the　contrary　spatial　order；　calling　right　that　which　is　to　our　left；　and　left　that　which　is　to　our　right。　We　observe；　however；　in　the　things　themselves　none　of　these　distinctions；　indeed　if　they　are　turned　round　we　proceed　to　speak　of　the　opposite　parts　as　right　and　left；　a　boy　land　below；　front　and　back。　Hence　it　is　remarkable　that　the　Pythagoreans　should　have　spoken　of　these　two　principles；　right　and　left；　only；　to　the　exclusion　of　the　other　four；　which　have　as　good　a　title　as　they。　There　is　no　less　difference　between　above　and　below　or　front　and　back　in　animals　generally　than　between　right　and　left。　The　difference　is　sometimes　only　one　of　function；　sometimes　also　one　of　shape；　and　while　the　distinction　of　above　and　below　is　characteristic　of　all　animate　things；　whether　plants　or　animals；　that　of　right　and　left　is　not　found　in　plants。　Further；　inasmuch　as　length　is　prior　to　breadth；　if　above　is　the　principle　of　length；　right　of　breadth；　and　if　the　principle　of　that　which　is　prior　is　itself　prior；　then　above　will　be　prior　to　right；　or　let　us　say；　since　'prior'　is　ambiguous；　prior　in　order　of　generation。　If；　in　addition；　above　is　the　region　from　which　movement　originates；　right　the　region　in　which　it　starts；　front　the　region　to　which　it　is　directed；　then　on　this　ground　too　above　has　a　certain　original　character　as　compared　with　the　other　forms　of　position。　On　these　two　grounds；　then；　they　may　fairly　be　criticized；　first；　for　omitting　the　more　fundamental　principles；　and　secondly；　for　thinking　that　the　two　they　mentioned　were　attributable　equally　to　everything。　　　Since　we　have　already　determined　that　functions　of　this　kind　belong　to　things　which　possess；　a　principle　of　movement；　and　that　the　heaven　is　animate　and　possesses　a　principle　of　movement；　clearly　the　heaven　must　also　exhibit　above　and　below；　right　and　left。　We　need　not　be　troubled　by　the　question；　arising　from　the　spherical　shape　of　the　world；　how　there　can　be　a　distinction　of　right　and　left　within　it；　all　parts　being　alike　and　all　for　ever　in　motion。　We　must　think　of　the　world　as　of　something　in　which　right　differs　from　left　in　shape　as　well　as　in　other　respects；　which　subsequently　is　included　in　a　sphere。　The　difference　of　function　will　persist；　but　will　appear　not　to　by　reason　of　the　regularity　of　shape。　In　the　same　fashion　must　we　conceive　of　the　beginning　of　its　movement。　For　even　if　it　never　began　to　move；　yet　it　must　possess　a　principle　from　which　it　would　have　begun　to　move　if　it　had　begun；　and　from　which　it　would　begin　again　if　it　came　to　a　stand。　Now　by　its　length　I　mean　the　interval　between　its　poles；　one　pole　being　above　and　the　other　below；　for　two　hemispheres　are　specially　distinguished　from　all　others　by　the　immobility　of　the　poles。　Further；　by　'transverse'　in　the　universe　we　commonly　mean；　not　above　and　below；　but　a　direction　crossing　the　line　of　the　poles；　which；　by　implication；　is　length：　for　transverse　motion　is　motion　crossing　motion　up　and　down。　Of　the　poles；　that　which　we　see　above　us　is　the　lower　region；　and　that　which　we　do　not　see　is　the　upper。　For　right　in　anything　is；　as　we　say；　the　region　in　which　locomotion　originates；　and　the　rotation　of　the　heaven　originates　in　the　region　from　which　the　stars　rise。　So　this　will　be　the　right；　and　the　region　where　they　set　the　left。　If　then　they　begin　from　the　right　and　move　round　to　the　right；　the　upper　must　be　the　unseen　pole。　For　if　it　is　the　pole　we　see；　the　movement　will　be　leftward；　which　we　deny　to　be　the　fact。　Clearly　then　the　invisible　pole　is　above。　And　those　who　live　in　the　other　hemisphere　are　above　and　to　the　right；　while　we　are　below　and　to　the　left。　This　is　just　the　opposite　of　the　view　of　the　Pythagoreans；　who　make　us　above　and　on　the　right　side　and　those　in　the　other　hemisphere　below　and　on　the　left　side；　the　fact　being　the　exact　opposite。　Relatively；　however；　to　the　secondary　revolution；　I　mean　that　of　the　planets；　we　are　above　and　on　the　right　and　they　are　below　and　on　the　left。　For　the　principle　of　their　movement　has　the　reverse　position；　since　the　movement　itself　is　the　contrary　of　the　other：　hence　it　follows　that　we　are　at　its　beginning　and　they　at　its　end。　Here　we　may　end　our　discussion　of　the　distinctions　of　parts　created　by　the　three　dimensions　and　of　the　consequent　differences　of　position。
  3
  Since　circular　motion　is　not　the　contrary　of　the　reverse　circular　motion；　we　must　consider　why　there　is　more　than　one　motion；　though　we　have　to　pursue　our　inquiries　at　a　distance…a　distance　created　not　so　much　by　our　spatial　position　as　by　the　fact　that　our　senses　enable　us　to　perceive　very　few　of　the　attributes　of　the　heavenly　bodies。　But　let　not　that　deter　us。　The　reason　must　be　sought　in　the　following　facts。　Everything　which　has　a　function　exists　for　its　function。　The　activity　of　God　is　immortality；　i。e。　eternal　life。　Therefore　the　movement　of　that　which　is　divine　must　be　eternal。　But　such　is　the　heaven；　viz。　a　divine　body；　and　for　that　reason　to　it　is　given　the　circular　body　whose　nature　it　is　to　move　always　in　a　circle。　Why；　then；　is　not　the　whole　body　of　the　heaven　of　the　same　character　as　that　part？　Because　there　must　be　something　at　rest　at　the　centre　of　the　revolving　body；　and　of　that　body　no　part　can　be　at　rest；　either　elsewhere　or　at　the　centre。　It　could　do　so　only　if　the　body's　natural　movement　were　towards　the　centre。　But　the　circular　movement　is　natural；　since　otherwise　it　could　not　be　eternal：　for　nothing　unnatural　is　eternal。　The　unnatural　is　subsequent　to　the　natural；　being　a　derangement　of　the　natural　which　occurs　in　the　course　of　its　generation。　Earth　then　has　to　exist；　for　it　is　earth　which　is　at　rest　at　the　centre。　（At　present　we　may　take　this　for　granted：　it　shall　be　explained　later。）　But　if　earth　must　exist；　so　must　fire。　For；　if　one　of　a　pair　of　contraries　naturally　exists；　the　other；　if　it　is　really　contrary；　exists　also　naturally。　In　some　form　it　must　be　present；　since　the　matter　of