on sense and the sensible-第5章

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　　Those　who　nowadays　introduce　such　flavours　into　beverages　deforce



our　sense　of　pleasure　by　habituating　us　to　them；　until；　from　two



distinct　kinds　of　sensations　combined；　pleasure　arises　as　it　might



from　one　simple　kind。



　　Of　this　species　of　odour　man　alone　is　sensible；　the　other；　viz。　that



correlated　with　Tastes；　is；　as　has　been　said　before；　perceptible



also　to　the　lower　animals。　And　odours　of　the　latter　sort；　since



their　pleasureableness　depends　upon　taste；　are　divided　into　as　many



species　as　there　are　different　tastes；　but　we　cannot　go　on　to　say　this



of　the　former　kind　of　odour；　since　its　nature　is　agreeable　or



disagreeable　per　se。　The　reason　why　the　perception　of　such　odours　is



peculiar　to　man　is　found　in　the　characteristic　state　of　man's　brain。



For　his　brain　is　naturally　cold；　and　the　blood　which　it　contains　in



its　vessels　is　thin　and　pure　but　easily　cooled　（whence　it　happens　that



the　exhalation　arising　from　food；　being　cooled　by　the　coldness　of　this



region；　produces　unhealthy　rheums）；　therefore　it　is　that　odours　of



such　a　species　have　been　generated　for　human　beings；　as　a　safeguard　to



health。　This　is　their　sole　function；　and　that　they　perform　it　is



evident。　For　food；　whether　dry　or　moist；　though　sweet　to　taste；　is



often　unwholesome；　whereas　the　odour　arising　from　what　is　fragrant；



that　odour　which　is　pleasant　in　its　own　right；　is；　so　to　say；　always



beneficial　to　persons　in　any　state　of　bodily　health　whatever。



　　For　this　reason；　too；　the　perception　of　odour　＇in　general＇



effected　through　respiration；　not　in　all　animals；　but　in　man　and



certain　other　sanguineous　animals；　e。g。　quadrupeds；　and　all　that



participate　freely　in　the　natural　substance　air；　because　when



odours；　on　account　of　the　lightness　of　the　heat　in　them；　mount　to



the　brain；　the　health　of　this　region　is　thereby　promoted。　For　odour；



as　a　power；　is　naturally　heat…giving。　Thus　Nature　has　employed



respiration　for　two　purposes：　primarily　for　the　relief　thereby　brought



to　the　thorax；　secondarily　for　the　inhalation　of　odour。　For　while　an



animal　is　inhaling；…　odour　moves　in　through　its　nostrils；　as　it　were



'from　a　side…entrance。'



　　But　the　perception　of　the　second　class　of　odours　above　described



＇does　not　belong　to　all　animal；　but＇　is　confined　to　human　beings；



because　man's　brain　is；　in　proportion　to　his　whole　bulk；　larger　and



moister　than　the　brain　of　any　other　animal。　This　is　the　reason　of



the　further　fact　that　man　alone；　so　to　speak；　among　animals



perceives　and　takes　pleasure　in　the　odours　of　flowers　and　such　things。



For　the　heat　and　stimulation　set　up　by　these　odours　are　commensurate



with　the　excess　of　moisture　and　coldness　in　his　cerebral　region。　On



all　the　other　animals　which　have　lungs；　Nature　has　bestowed　their



due　perception　of　one　of　the　two　kinds　of　odour　＇i。e。　that　connected



with　nutrition＇　through　the　act　of　respiration；　guarding　against　the



needless　creation　of　two　organs　of　sense；　for　in　the　fact　that　they



respire　the　other　animals　have　already　sufficient　provision　for



their　perception　of　the　one　species　of　odour　only；　as　human　beings



have　for　their　perception　of　both。



　　But　that　creatures　which　do　not　respire　have　the　olfactory　sense



is　evident。　For　fishes；　and　all　insects　as　a　class；　have；　thanks　to



the　species　of　odour　correlated　with　nutrition；　a　keen　olfactory　sense



of　their　proper　food　from　a　distance；　even　when　they　are　very　far　away



from　it；　such　is　the　case　with　bees；　and　also　with　the　class　of



small　ants；　which　some　denominate　knipes。　Among　marine　animals；　too；



the　murex　and　many　other　similar　animals　have　an　acute　perception　of



their　food　by　its　odour。



　　It　is　not　equally　certain　what　the　organ　is　whereby　they　so



perceive。　This　question；　of　the　organ　whereby　they　perceive　odour；　may



well　cause　a　difficulty；　if　we　assume　that　smelling　takes　place　in



animals　only　while　respiring　（for　that　this　is　the　fact　is　manifest　in



all　the　animals　which　do　respire）；　whereas　none　of　those　just



mentioned　respires；　and　yet　they　have　the　sense　of　smell…　unless；



indeed；　they　have　some　other　sense　not　included　in　the　ordinary



five。　This　supposition　is；　however；　impossible。　For　any　sense　which



perceives　odour　is　a　sense　of　smell；　and　this　they　do　perceive；　though



probably　not　in　the　same　way　as　creatures　which　respire；　but　when



the　latter　are　respiring　the　current　of　breath　removes　something



that　is　laid　like　a　lid　upon　the　organ　proper　（which　explains　why　they



do　not　perceive　odours　when　not　respiring）；　while　in　creatures　which



do　not　respire　this　is　always　off：　just　as　some　animals　have　eyelids



on　their　eyes；　and　when　these　are　not　raised　they　cannot　see；



whereas　hard…eyed　animals　have　no　lids；　and　consequently　do　not



need；　besides　eyes；　an　agency　to　raise　the　lids；　but　see　straightway



＇without　intermission＇　from　the　actual　moment　at　which　it　is　first



possible　for　them　to　do　so　＇i。e。　from　the　moment　when　an　object



first　comes　within　their　field　of　vision＇。



　　Consistently　with　what　has　been　said　above；　not　one　of　the　lower



animals　shows　repugnance　to　the　odour　of　things　which　are



essentially　ill…smelling；　unless　one　of　the　latter　is　positively



pernicious。　They　are　destroyed；　however；　by　these　things；　just　as



human　beings　are；　i。e。　as　human　beings　get　headaches　from；　and　are



often　asphyxiated　by；　the　fumes　of　charcoal；　so　the　lower　animals



perish　from　the　strong　fumes　of　brimstone　and　bituminous　substances；



and　it　is　owing　to　experience　of　such　effects　that　they　shun　these。



For　the　disagreeable　odour　in　itself　they　care　nothing　whatever



（though　the　odours　of　many　plants　are　essentially　disagreeable）；



unless；　indeed；　it　has　some　effect　upon　the　taste　of　their　food。



　　The　senses　making　up　an　odd　number；　and　an　odd　number　having



always　a　middle　unit；　the　sense　of　smell　occupies　in　itself　as　it　were



a　middle　position　between　the　tactual　senses；　i。e。　Touch　and　Taste；



and　those　which　perceive　through　a　medium；　i。e。　Sight　and　Hearing。



Hence　the　object　of　smell；　too；　is　an　affection　of　nutrient　substances



（which　fall　within　the　class　of　Tangibles）；　and　is　also　an　affection



of　the　audible　and　the　visible；　whence　it　is　that　creatures　have　the



sense　of　smell　both　in　air　and　water。　Accordingly；　the　object　of　smell



is　something　common　to　both　of　these　provinces；　i。e。　it　appertains



both　to　the　tangible　on　the　one　hand；　and　on　the　other　to　the



audible　and　translucent。　Hence　the　propriety　of　the　figure　by　which　it



has　been　described　by　us　as　an　immersion　or　washing　of　dryness　in



the　Moist　and　Fluid。　Such　then　must　be　our　account　of　the　sense　in



which　one　is　or　is　not　entitled　to　speak　of　the　odorous　as　having



species。



　　The　theory　held　by　certain　of　the　Pythagoreans；　that　some　animals



are　nourished　by　odours　alone；　is　unsound。　For；　in　the　first　place；　we



see　that　food　must　be　composite；　since　the　bodies　nourished　by　it



are　not　simple。　This　explains　why　waste　matter　is　secreted　from



food；　either　within　the　organisms；　or；　as　in　plants；　outside　them。　But



since　even　water　by　itself　alone；　that　is；　when　unmixed；　will　not



suffice　for　food…　for　anything　which　is　to　form　a　consistency　must　be



corporeal…；　it　is　still　much　less　conceivable　that　air　should　be　so



corporealized　＇and　thus　fitted　to　be　food＇。　But；　besides　this；　we



see　that　all　animals　have　a　receptacle　for　food；　from　which；　when　it



has　entered；　the　body　absorbs　it。　Now；　the　organ　which　perceives　odour



is　in　the　head；　and　odour　enters　with　the　inhalation　of　the　breath；　so



that　it　goes　to　the　respiratory　region。　It　is　plain；　therefore；　that



odour；　qua　odour；　does　not　contribute　to　nutrition；　that；　however；



it　is　serviceable　to　health　is　equally　plain；　as　well　by　immediate



perception　as　from　the　arguments　above　employed；　so　that　odour　is　in



relation　to　general　health　what　savour　is　in　the　province　of　nutrition



and　in　relation　to　the　bodies　nourished。



　　This　then　must　conclude　our　discussion　of　the　several　organs　of



sense…perception。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　6







　　One　might　ask：　if　every　body　is　infinitely　divisible；　are　its



sensible　qualities…　Colour；　Savour；　Odour；　Sound；　Weight；　Cold　or



Heat；　＇Heaviness　or＇　Lightness；　Hardness　or　Softness…also　infinitely



divisible？　Or；　is　this　impossible？



　　＇One　might　well　ask　this　question＇；　because　each　of　them　is



productive　of　sense…perception；　since；　in　fact；　all　derive　their



name　＇of　'sensible　qualities'＇　from　the　very　circumstance　of　their



being　able　to　stimulate　this。　Hence；　＇if　this　is　so＇　both　our



perception　of　them　should　likewise　be　divisible　to　infinity；　and　every



part　of　a　body　＇however　small＇　should　be　a　perceptible　magnitude。



For　it　is　impossible；　e。g。　to　see　a　thing　which　is　white　but　not　of



a　certain　magnitude。



　　Since　if　it　were　not　so；　＇if　its　sensible　qualities　were　not



divisible；　pari　passu　with　body＇；　we　might　conceive　a　body　existing



but　having　no　colour；　or　weight；　or　any　such　quality；　accordingly



not　perceptible　at　all。　For　these　qualities　are　the　objects　of



sense…perception。　On　this　supposition；　every　perceptible　object　should



be　regarded　as　composed　not　of　perceptible　＇but　of　imperceptible＇



parts。　Yet　it　must　＇be　really　composed　of　perceptible　parts＇；　since



assuredly　it　does　not　consist　of　mathematical　＇and　therefore　purely



abstract　and　non…sensible＇　quantities。　Again；　by　what　faculty　should



we　discern　and　cognize　these　＇hypothetical　real　things　without



sensible　qualities＇？　Is　it　by　Reason？　But　they　are　not　objects　of



Reason；　nor　does　reason　apprehend　objects　in　space；　except　when　it



acts　in　conjunction　with　sense…perception。　At　the　same　time；　if　this



be　the　case　＇that　there　are　magnitudes；　physically　real；　but　without



sensible　quality＇；　it　seems　to　tell　in　favour　of　the　atomistic



hypothesis；　for　thus；　indeed；　＇by　accepting　this　hypothesis＇；　the



question　＇with　which　this　chapter　begins＇　might　be　solved



＇negatively＇。　But　it　is　impossible　＇to　accept　this　hypothesis＇。　Our



views　on　the　subject　of　atoms　are　to　be　found　in　our　treatise　on



Movement。



　　The　solution　of　these　questions　will　bring　with　it　also　the　answer



to　the　question　why　the　species　of　Colour；　Taste；　Sound；　and　other



sensible　qualities　are　limited。　For　in　all　classes　of　things　lying



between　extremes　the　intermediates　must　be　limited。　But　contraries　are



extremes；　and　every　object　of　sense…perception　involves　contrariety：



e。g。　in　Colour；　White　x　Black；　in　Savour；　Sweet　x　Bitter；　and　in　all



the　other　sensibles　also　the　contraries　are　extremes。　Now；　that



which　is　continuous　is　divisible　into　an　infinite　number　of　unequal



parts；　but　into　a　finite　number　of　equal　parts；　while　that　which　is



not　per　se　continuous　is　divisi