on the motion of animals-第2章

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be　at　rest；　and　against　this　the　part　which　is　moved　will　support



itself　and　be　moved；　for　example；　if　it　move　one　of　its　parts；　for　one



part；　as　it　were；　supports　itself　against　another　part　at　rest。



　　But　about　things　without　life　which　are　moved　one　might　ask　the



question　whether　all　contain　in　themselves　both　that　which　is　at



rest　and　that　which　initiates　movement；　and　whether　they　also；　for



instance　fire；　earth；　or　any　other　inanimate　thing；　must　support



themselves　against　something　outside　which　is　at　rest。　Or　is　this



impossible　and　must　it　not　be　looked　for　rather　in　those　primary



causes　by　which　they　are　set　in　motion？　For　all　things　without　life



are　moved　by　something　other；　and　the　origin　of　all　things　so　moved



are　things　which　move　themselves。　And　out　of　these　we　have　spoken



about　animals　（for　they　must　all　have　in　themselves　that　which　is　at



rest；　and　without　them　that　against　which　they　are　supported）；　but



whether　there　is　some　higher　and　prime　mover　is　not　clear；　and　an



origin　of　that　kind　involves　a　different　discussion。　Animals　at　any



rate　which　move　themselves　are　all　moved　supporting　themselves　on　what



is　outside　them；　even　when　they　inspire　and　expire；　for　there　is　no



essential　difference　between　casting　a　great　and　a　small　weight；　and



this　is　what　men　do　when　they　spit　and　cough　and　when　they　breathe



in　and　breathe　out。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　5







　　But　is　it　only　in　that　which　moves　itself　in　place　that　there　must



be　a　point　at　rest；　or　does　this　hold　also　of　that　which　causes　its



own　qualitative　changes；　and　its　own　growth？　Now　the　question　of



original　generation　and　decay　is　different；　for　if　there　is；　as　we



hold；　a　primary　movement；　this　would　be　the　cause　of　generation　and



decay；　and　probably　of　all　the　secondary　movements　too。　And　as　in



the　universe；　so　in　the　animal　world　this　is　the　primary　movement；



when　the　creature　attains　maturity；　and　therefore　it　is　the　cause　of



growth；　when　the　creature　becomes　the　cause　of　its　own　growth；　and　the



cause　too　of　alteration。　But　if　this　is　not　the　primary　movement



then　the　point　at　rest　is　not　necessary。　However；　the　earliest



growth　and　alteration　in　the　living　creature　arise　through　another　and



by　other　channels；　nor　can　anything　possibly　be　the　cause　of　its　own



generation　and　decay；　for　the　mover　must　exist　before　the　moved；　the



begetter　before　the　begotten；　and　nothing　is　prior　to　itself。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　6







　　Now　whether　the　soul　is　moved　or　not；　and　how　it　is　moved　if　it　be



moved；　has　been　stated　before　in　our　treatise　concerning　it。　And　since



all　inorganic　things　are　moved　by　some　other　thing…　and　the　manner



of　the　movement　of　the　first　and　eternally　moved；　and　how　the　first



mover　moves　it；　has　been　determined　before　in　our　Metaphysics；　it



remains　to　inquire　how　the　soul　moves　the　body；　and　what　is　the　origin



of　movement　in　a　living　creature。　For；　if　we　except　the　movement　of



the　universe；　things　with　life　are　the　causes　of　the　movement　of　all



else；　that　is　of　all　that　are　not　moved　by　one　another　by　mutual



impact。　And　so　all　their　motions　have　a　term　or　limit；　inasmuch　as　the



movements　of　things　with　life　have　such。　For　all　living　things　both



move　and　are　moved　with　some　object；　so　that　this　is　the　term　of　all



their　movement；　the　end；　that　is；　in　view。　Now　we　see　that　the



living　creature　is　moved　by　intellect；　imagination；　purpose；　wish；　and



appetite。　And　all　these　are　reducible　to　mind　and　desire。　For　both



imagination　and　sensation　are　on　common　ground　with　mind；　since　all



three　are　faculties　of　judgement　though　differing　according　to



distinctions　stated　elsewhere。　Will；　however；　impulse；　and　appetite；



are　all　three　forms　of　desire；　while　purpose　belongs　both　to　intellect



and　to　desire。　Therefore　the　object　of　desire　or　of　intellect　first



initiates　movement；　not；　that　is；　every　object　of　intellect；　only



the　end　in　the　domain　of　conduct。　Accordingly　among　goods　that　which



moves　is　a　practical　end；　not　the　good　in　its　whole　extent。　For　it



initiates　movement　only　so　far　as　something　else　is　for　its　sake；　or



so　far　as　it　is　the　object　of　that　which　is　for　the　sake　of



something　else。　And　we　must　suppose　that　a　seeming　good　may　take　the



room　of　actual　good；　and　so　may　the　pleasant；　which　is　itself　a



seeming　good。　From　these　considerations　it　is　clear　that　in　one　regard



that　which　is　eternally　moved　by　the　eternal　mover　is　moved　in　the



same　way　as　every　living　creature；　in　another　regard　differently；



and　so　while　it　is　moved　eternally；　the　movement　of　living　creatures



has　a　term。　Now　the　eternal　beautiful；　and　the　truly　and　primarily



good　（which　is　not　at　one　time　good；　at　another　time　not　good）；　is　too



divine　and　precious　to　be　relative　to　anything　else。　The　prime　mover



then　moves；　itself　being　unmoved；　whereas　desire　and　its　faculty　are



moved　and　so　move。　But　it　is　not　necessary　for　the　last　in　the　chain



of　things　moved　to　move　something　else；　wherefore　it　is　plainly



reasonable　that　motion　in　place　should　be　the　last　of　what　happens



in　the　region　of　things　happening；　since　the　living　creature　is



moved　and　goes　forward　by　reason　of　desire　or　purpose；　when　some



alteration　has　been　set　going　on　the　occasion　of　sensation　or



imagination。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　7







　　But　how　is　it　that　thought　（viz。　sense；　imagination；　and　thought



proper）　is　sometimes　followed　by　action；　sometimes　not；　sometimes　by



movement；　sometimes　not？　What　happens　seems　parallel　to　the　case　of



thinking　and　inferring　about　the　immovable　objects　of　science。　There



the　end　is　the　truth　seen　（for；　when　one　conceives　the　two



premisses；　one　at　once　conceives　and　comprehends　the　conclusion）；



but　here　the　two　premisses　result　in　a　conclusion　which　is　an



action…　for　example；　one　conceives　that　every　man　ought　to　walk；　one



is　a　man　oneself：　straightway　one　walks；　or　that；　in　this　case；　no　man



should　walk；　one　is　a　man：　straightway　one　remains　at　rest。　And　one　so



acts　in　the　two　cases　provided　that　there　is　nothing　in　the　one　case



to　compel　or　in　the　other　to　prevent。　Again；　I　ought　to　create　a　good；



a　house　is　good：　straightway　I　make　a　house。　I　need　a　covering；　a　coat



is　a　covering：　I　need　a　coat。　What　I　need　I　ought　to　make；　I　need　a



coat：　I　make　a　coat。　And　the　conclusion　I　must　make　a　coat　is　an



action。　And　the　action　goes　back　to　the　beginning　or　first　step。　If



there　is　to　be　a　coat；　one　must　first　have　B；　and　if　B　then　A；　so



one　gets　A　to　begin　with。　Now　that　the　action　is　the　conclusion　is



clear。　But　the　premisses　of　action　are　of　two　kinds；　of　the　good　and



of　the　possible。



　　And　as　in　some　cases　of　speculative　inquiry　we　suppress　one



premise　so　here　the　mind　does　not　stop　to　consider　at　all　an　obvious



minor　premise；　for　example　if　walking　is　good　for　man；　one　does　not



dwell　upon　the　minor　'I　am　a　man'。　And　so　what　we　do　without



reflection；　we　do　quickly。　For　when　a　man　actualizes　himself　in



relation　to　his　object　either　by　perceiving；　or　imagining　or



conceiving　it；　what　he　desires　he　does　at　once。　For　the　actualizing　of



desire　is　a　substitute　for　inquiry　or　reflection。　I　want　to　drink；



says　appetite；　this　is　drink；　says　sense　or　imagination　or　mind：



straightway　I　drink。　In　this　way　living　creatures　are　impelled　to　move



and　to　act；　and　desire　is　the　last　or　immediate　cause　of　movement；　and



desire　arises　after　perception　or　after　imagination　and　conception。



And　things　that　desire　to　act　now　create　and　now　act　under　the



influence　of　appetite　or　impulse　or　of　desire　or　wish。



　　The　movements　of　animals　may　be　compared　with　those　of　automatic



puppets；　which　are　set　going　on　the　occasion　of　a　tiny　movement；　the



levers　are　released；　and　strike　the　twisted　strings　against　one



another；　or　with　the　toy　wagon。　For　the　child　mounts　on　it　and　moves



it　straight　forward；　and　then　again　it　is　moved　in　a　circle　owing　to



its　wheels　being　of　unequal　diameter　（the　smaller　acts　like　a　centre



on　the　same　principle　as　the　cylinders）。　Animals　have　parts　of　a



similar　kind；　their　organs；　the　sinewy　tendons　to　wit　and　the　bones；



the　bones　are　like　the　wooden　levers　in　the　automaton；　and　the　iron；



the　tendons　are　like　the　strings；　for　when　these　are　tightened　or



leased　movement　begins。　However；　in　the　automata　and　the　toy　wagon



there　is　no　change　of　quality；　though　if　the　inner　wheels　became



smaller　and　greater　by　turns　there　would　be　the　same　circular　movement



set　up。　In　an　animal　the　same　part　has　the　power　of　becoming　now



larger　and　now　smaller；　and　changing　its　form；　as　the　parts　increase



by　warmth　and　again　contract　by　cold　and　change　their　quality。　This



change　of　quality　is　caused　by　imaginations　and　sensations　and　by



ideas。　Sensations　are　obviously　a　form　of　change　of　quality；　and



imagination　and　conception　have　the　same　effect　as　the　objects　so



imagined　and　conceived　For　in　a　measure　the　form　conceived　be　it　of



hot　or　cold　or　pleasant　or　fearful　is　like　what　the　actual　objects



would　be；　and　so　we　shudder　and　are　frightened　at　a　mere　idea。　Now　all



these　affections　involve　changes　of　quality；　and　with　those　changes



some　parts　of　the　body　enlarge；　others　grow　smaller。　And　it　is　not



hard　to　see　that　a　small　change　occurring　at　the　centre　makes　great



and　numerous　changes　at　the　circumference；　just　as　by　shifting　the



rudder　a　hair's　breadth　you　get　a　wide　deviation　at　the　prow。　And



further；　when　by　reason　of　heat　or　cold　or　some　kindred　affection　a



change　is　set　up　in　the　region　of　the　heart；　even　in　an



imperceptibly　small　part　of　the　heart；　it　produces　a　vast　difference



in　the　periphery　of　the　body；…　blushing；　let　us　say；　or　turning　white；



goose…skin　and　shivers　and　their　opposites。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　8







　　But　to　return；　the　object　we　pursue　or　avoid　in　the　field　of



action　is；　as　has　been　explained；　the　original　of　movement；　and　upon



the　conception　and　imagination　of　this　there　necessarily　follows　a



change　in　the　temperature　of　the　body。　For　what　is　painful　we　avoid；



what　is　pleasing　we　pursue。　We　are；　however；　unconscious　of　what



happens　in　the　minute　parts；　still　anything　painful　or　pleasing　is



generally　speaking　accompanied　by　a　definite　change　of　temperature



in　the　body。　One　may　see　this　by　considering　the　affections。　Blind



courage　and　panic　fears；　erotic　motions；　and　the　rest　of　the　corporeal



affections；　pleasant　and　painful；　are　all　accompanied　by　a　change　of



temperature；　some　in　a　particular　member；　others　in　the　body



generally。　So；　memories　and　anticipations；　using　as　it　were　the



reflected　images　of　these　pleasures　and　pains；　are　now　more　and　now



less　causes　of　the　same　changes