on sense and the sensible- 第2部分

occurred　to　him　to　ask　why；　if　his　theory　be　true；　the　eye　alone　sees；



while　none　of　the　other　things　in　which　images　are　reflected　do　so。



　　True；　then；　the　visual　organ　proper　is　composed　of　water；　yet　vision



appertains　to　it　not　because　it　is　so　composed；　but　because　it　is



translucent…　a　property　common　alike　to　water　and　to　air。　But　water



is　more　easily　confined　and　more　easily　condensed　than　air；



wherefore　it　is　that　the　pupil；　i。e。　the　eye　proper；　consists　of



water。　That　it　does　so　is　proved　by　facts　of　actual　experience。　The



substance　which　flows　from　eyes　when　decomposing　is　seen　to　be



water；　and　this　in　undeveloped　embryos　is　remarkably　cold　and



glistening。　In　sanguineous　animals　the　white　of　the　eye　is　fat　and



oily；　in　order　that　the　moisture　of　the　eye　may　be　proof　against



freezing。　Wherefore　the　eye　is　of　all　parts　of　the　body　the　least



sensitive　to　cold：　no　one　ever　feels　cold　in　the　part　sheltered　by　the



eyelids。　The　eyes　of　bloodless　animals　are　covered　with　a　hard　scale



which　gives　them　similar　protection。



　　It　is；　to　state　the　matter　generally；　an　irrational　notion　that



the　eye　should　see　in　virtue　of　something　issuing　from　it；　that　the



visual　ray　should　extend　itself　all　the　way　to　the　stars；　or　else　go



out　merely　to　a　certain　point；　and　there　coalesce；　as　some　say；　with



rays　which　proceed　from　the　object。　It　would　be　better　to　suppose　this



coalescence　to　take　place　in　the　fundament　of　the　eye　itself。　But　even



this　would　be　mere　trifling。　For　what　is　meant　by　the　'coalescence'　of



light　with　light？　Or　how　is　it　possible？　Coalescence　does　not　occur



between　any　two　things　taken　at　random。　And　how　could　the　light　within



the　eye　coalesce　with　that　outside　it？　For　the　environing　membrane



comes　between　them。



　　That　without　light　vision　is　impossible　has　been　stated　elsewhere；



but；　whether　the　medium　between　the　eye　and　its　objects　is　air　or



light；　vision　is　caused　by　a　process　through　this　medium。



　　Accordingly；　that　the　inner　part　of　the　eye　consists　of　water　is



easily　intelligible；　water　being　translucent。



　　Now；　as　vision　outwardly　is　impossible　without　＇extra…organic＇



light；　so　also　it　is　impossible　inwardly　＇without　light　within　the



organ＇。　There　must；　therefore；　be　some　translucent　medium　within　the



eye；　and；　as　this　is　not　air；　it　must　be　water。　The　soul　or　its



perceptive　part　is　not　situated　at　the　external　surface　of　the　eye；



but　obviously　somewhere　within：　whence　the　necessity　of　the　interior



of　the　eye　being　translucent；　i。e。　capable　of　admitting　light。　And



that　it　is　so　is　plain　from　actual　occurrences。　It　is　matter　of



experience　that　soldiers　wounded　in　battle　by　a　sword　slash　on　the



temple；　so　inflicted　as　to　sever　the　passages　of　＇i。e。　inward　from＇



the　eye；　feel　a　sudden　onset　of　darkness；　as　if　a　lamp　had　gone　out；



because　what　is　called　the　pupil；　i。e。　the　translucent；　which　is　a



sort　of　inner　lamp；　is　then　cut　off　＇from　its　connexion　with　the



soul＇。



　　Hence；　if　the　facts　be　at　all　as　here　stated；　it　is　clear　that…　if



one　should　explain　the　nature　of　the　sensory　organs　in　this　way；



i。e。　by　correlating　each　of　them　with　one　of　the　four　elements；…　we



must　conceive　that　the　part　of　the　eye　immediately　concerned　in　vision



consists　of　water；　that　the　part　immediately　concerned　in　the



perception　of　sound　consists　of　air；　and　that　the　sense　of　smell



consists　of　fire。　（I　say　the　sense　of　smell；　not　the　organ。）　For　the



organ　of　smell　is　only　potentially　that　which　the　sense　of　smell；　as



realized；　is　actually；　since　the　object　of　sense　is　what　causes　the



actualization　of　each　sense；　so　that　it　（the　sense）　must　（at　the



instant　of　actualization）　be　（actually）　that　which　before　（the



moment　of　actualization）　it　was　potentially。　Now；　odour　is　a



smoke…like　evaporation；　and　smoke…like　evaporation　arises　from　fire。



This　also　helps　us　to　understand　why　the　olfactory　organ　has　its



proper　seat　in　the　environment　of　the　brain；　for　cold　matter　is



potentially　hot。　In　the　same　way　must　the　genesis　of　the　eye　be



explained。　Its　structure　is　an　offshoot　from　the　brain；　because　the



latter　is　the　moistest　and　coldest　of　all　the　bodily　parts。



　　The　organ　of　touch　proper　consists　of　earth；　and　the　faculty　of



taste　is　a　particular　form　of　touch。　This　explains　why　the　sensory



organ　of　both　touch　and　taste　is　closely　related　to　the　heart。　For　the



heart　as　being　the　hottest　of　all　the　bodily　parts；　is　the



counterpoise　of　the　brain。



　　This　then　is　the　way　in　which　the　characteristics　of　the　bodily



organs　of　sense　must　be　determined。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　3







　　Of　the　sensibles　corresponding　to　each　sensory　organ；　viz。　colour；



sound；　odour；　savour；　touch；　we　have　treated　in　On　the　Soul　in　general



terms；　having　there　determined　what　their　function　is；　and　what　is



implied　in　their　becoming　actualized　in　relation　to　their　respective



organs。　We　must　next　consider　what　account　we　are　to　give　of　any　one



of　them；　what；　for　example；　we　should　say　colour　is；　or　sound；　or



odour；　or　savour；　and　so　also　respecting　＇the　object　of＇　touch。　We



begin　with　colour。



　　Now；　each　of　them　may　be　spoken　of　from　two　points　of　view；　i。e。



either　as　actual　or　as　potential。　We　have　in　On　the　Soul　explained



in　what　sense　the　colour；　or　sound；　regarded　as　actualized　＇for



sensation＇　is　the　same　as；　and　in　what　sense　it　is　different　from；　the



correlative　sensation；　the　actual　seeing　or　hearing。　The　point　of



our　present　discussion　is；　therefore；　to　determine　what　each



sensible　object　must　be　in　itself；　in　order　to　be　perceived　as　it　is



in　actual　consciousness。



　　We　have　already　in　On　the　Soul　stated　of　Light　that　it　is　the　colour



of　the　Translucent；　＇being　so　related　to　it＇　incidentally；　for



whenever　a　fiery　element　is　in　a　translucent　medium　presence　there



is　Light；　while　the　privation　of　it　is　Darkness。　But　the



'Translucent'；　as　we　call　it；　is　not　something　peculiar　to　air；　or



water；　or　any　other　of　the　bodies　usually　called　translucent；　but　is　a



common　'nature'　and　power；　capable　of　no　separate　existence　of　its



own；　but　residing　in　these；　and　subsisting　likewise　in　all　other



bodies　in　a　greater　or　less　degree。　As　the　bodies　in　which　it　subsists



must　have　some　extreme　bounding　surface；　so　too　must　this。　Here；　then；



we　may　say　that　Light　is　a　'nature'　inhering　in　the　Translucent　when



the　latter　is　without　determinate　boundary。　But　it　is　manifest　that；



when　the　Translucent　is　in　determinate　bodies；　its　bounding　extreme



must　be　something　real；　and　that　colour　is　just　this　'something'　we



are　plainly　taught　by　facts…colour　being　actually　either　at　the



external　limit；　or　being　itself　that　limit；　in　bodies。　Hence　it　was



that　the　Pythagoreans　named　the　superficies　of　a　body　its　'hue'；　for



'hue'；　indeed；　lies　at　the　limit　of　the　body；　but　the　limit　of　the



body；　is　not　a　real　thing；　rather　we　must　suppose　that　the　same



natural　substance　which；　externally；　is　the　vehicle　of　colour　exists



＇as　such　a　possible　vehicle＇　also　in　the　interior　of　the　body。



　　Air　and　water；　too　＇i。e。　as　well　as　determinately　bounded　bodies＇



are　seen　to　possess　colour；　for　their　brightness　is　of　the　nature　of



colour。　But　the　colour　which　air　or　sea　presents；　since　the　body　in



which　it　resides　is　not　determinately　bounded；　is　not　the　same　when



one　approaches　and　views　it　close　by　as　it　is　when　one　regards　it　from



a　distance；　whereas　in　determinate　bodies　the　colour　presented　is



definitely　fixed；　unless；　indeed；　when　the　atmospheric　environment



causes　it　to　change。　Hence　it　is　clear　that　that　in　them　which　is



susceptible　of　colour　is　in　both　cases　the　same。　It　is　therefore　the



Translucent；　according　to　the　degree　to　which　it　subsists　in　bodies



（and　it　does　so　in　all　more　or　less）；　that　causes　them　to　partake　of



colour。　But　since　the　colour　is　at　the　extremity　of　the　body；　it



must　be　at　the　extremity　of　the　Translucent　in　the　body。　Whence　it



follows　that　we　may　define　colour　as　the　limit　of　the　Translucent　in



determinately　bounded　body。　For　whether　we　consider　the　special



class　of　bodies　called　translucent；　as　water　and　such　others；　or



determinate　bodies；　which　appear　to　possess　a　fixed　colour　of　their



own；　it　is　at　the　exterior　bounding　surface　that　all　alike　exhibit



their　colour。



　　Now；　that　which　when　present　in　air　produces　light　may　be　present



also　in　the　Translucent　which　pervades　determinate　bodies；　or　again；



it　may　not　be　present；　but　there　may　be　a　privation　of　it。



Accordingly；　as　in　the　case　of　air　the　one　condition　is　light；　the



other　darkness；　in　the　same　way　the　colours　White　and　Black　are



generated　in　determinate　bodies。



　　We　must　now　treat　of　the　other　colours；　reviewing　the　several



hypotheses　invented　to　explain　their　genesis。



　　（1）　It　is　conceivable　that　the　White　and　the　Black　should　be



juxtaposed　in　quantities　so　minute　that　＇a　particle　of＇　either



separately　would　be　invisible；　though　the　joint　product　＇of　two



particles；　a　black　and　a　white＇　would　be　visible；　and　that　they　should



thus　have　the　other　colours　for　resultants。　Their　product　could；　at



all　events；　appear　neither　white　nor　black；　and；　as　it　must　have



some　colour；　and　can　have　neither　of　these；　this　colour　must　be　of　a



mixed



character…　in　fact；　a　species　of　colour　different　from　either。　Such；



then；　is　a　possible　way　of　conceiving　the　existence　of　a　plurality



of　colours　besides　the　White　and　Black；　and　we　may　suppose　that　＇of



this　'plurality'＇　many　are　the　result　of　a　＇numerical＇　ratio；　for



the　blacks　and　whites　may　be　juxtaposed　in　the　ratio　of　3　to　2　or　of　3



to　4；　or　in　ratios　expressible　by　other　numbers；　while　some　may　be



juxtaposed　according　to　no　numerically　expressible　ratio；　but



ac