on sense and the sensible- 第5部分

＇sapid＇　moisture　has　been　burnt　out　of　them；　their　slag　is；　in　all



cases；　less　odorous　the　metals　＇than　the　metals　themselves＇。　Silver



and　tin　are　more　odorous　than　the　one　class　of　metals；　less　so　than



the　other；　inasmuch　as　they　are　water　＇to　a　greater　degree　than　the



former；　to　a　less　degree　than　the　latter＇。



　　Some　writers　look　upon　Fumid　exhalation；　which　is　a　compound　of



Earth　and　Air；　as　the　essence　of　Odour。　＇Indeed　all　are　inclined　to



rush　to　this　theory　of　Odour。＇　Heraclitus　implied　his　adherence　to



it　when　he　declared　that　if　all　existing　things　were　turned　into



Smoke；　the　nose　would　be　the　organ　to　discern　them　with。　All　writers



incline　to　refer　odour　to　this　cause　＇sc。　exhalation　of　some　sort＇；



but　some　regard　it　as　aqueous；　others　as　fumid；　exhalation；　while



others；　again；　hold　it　to　be　either。　Aqueous　exhalation　is　merely　a



form　of　moisture；　but　fumid　exhalation　is；　as　already　remarked；



composed　of　Air　and　Earth。　The　former　when　condensed　turns　into　water；



the　latter；　in　a　particular　species　of　earth。　Now；　it　is　unlikely　that



odour　is　either　of　these。　For　vaporous　exhalation　consists　of　mere



water　＇which；　being　tasteless；　is　inodorous＇；　and　fumid　exhalation



cannot　occur　in　water　at　all；　though；　as　has　been　before　stated；



aquatic　creatures　also　have　the　sense　of　smell。



　　Again；　the　exhalation　theory　of　odour　is　analogous　to　the　theory



of　emanations。　If；　therefore；　the　latter　is　untenable；　so；　too；　is　the



former。



　　It　is　clearly　conceivable　that　the　Moist；　whether　in　air　（for　air；



too；　is　essentially　moist）　or　in　water；　should　imbibe　the　influence



of；　and　have　effects　wrought　in　it　by；　the　Sapid　Dryness。　Moreover；　if



the　Dry　produces　in　moist　media；　i。e。　water　and　air；　an　effect　as　of



something　washed　out　in　them；　it　is　manifest　that　odours　must　be



something　analogous　to　savours。　Nay；　indeed；　this　analogy　is；　in



some　instances；　a　fact　＇registered　in　language＇；　for　odours　as　well　as



savours　are　spoken　of　as　pungent；　sweet；　harsh；　astringent　rich



＇='savoury'＇；　and　one　might　regard　fetid　smells　as　analogous　to　bitter



tastes；　which　explains　why　the　former　are　offensive　to　inhalation　as



the　latter　are　to　deglutition。　It　is　clear；　therefore；　that　Odour　is



in　both　water　and　air　what　Savour　is　in　water　alone。　This　explains　why



coldness　and　freezing　render　Savours　dull；　and　abolish　odours



altogether；　for　cooling　and　freezing　tend　to　annul　the　kinetic　heat



which　helps　to　fabricate　sapidity。



　　There　are　two　species　of　the　Odorous。　For　the　statement　of　certain



writers　that　the　odorous　is　not　divisible　into　species　is　false；　it　is



so　divisible。　We　must　here　define　the　sense　in　which　these　species　are



to　be　admitted　or　denied。



　　One　class　of　odours；　then；　is　that　which　runs　parallel；　as　has



been　observed；　to　savours：　to　odours　of　this　class　their



pleasantness　or　unpleasantness　belongs　incidentally。　For　owing　to



the　fact　that　Savours　are　qualities　of　nutrient　matter；　the　odours



connected　with　these　＇e。g。　those　of　a　certain　food＇　are　agreeable　as



long　as　animals　have　an　appetite　for　the　food；　but　they　are　not



agreeable　to　them　when　sated　and　no　longer　in　want　of　it；　nor　are　they



agreeable；　either；　to　those　animals　that　do　not　like　the　food　itself



which　yields　the　odours。　Hence；　as　we　observed；　these　odours　are



pleasant　or　unpleasant　incidentally；　and　the　same　reasoning　explains



why　it　is　that　they　are　perceptible　to　all　animals　in　common。



　　The　other　class　of　odours　consists　of　those　agreeable　in　their



essential　nature；　e。g。　those　of　flowers。　For　these　do　not　in　any



degree　stimulate　animals　to　food；　nor　do　they　contribute　in　any　way　to



appetite；　their　effect　upon　it；　if　any；　is　rather　the　opposite。　For



the　verse　of　Strattis　ridiculing　Euripides…







　　　　　　　　Use　not　perfumery　to　flavour　soup；







contains　a　truth。



　　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　sens