ration　is　the　windpipe；　and　the　organ　to　which　this　is　related　as　means　to　end　is　the　lungs。　The　latter　is　the　part　of　the　body　by　which　the　temperature　of　land　animals　is　raised　above　that　of　all　others。　But　what　primarily　requires　the　air　drawn　in　by　respiration　is　not　only　this　but　the　region　surrounding　the　heart。　That　is　why　when　animals　breathe　the　air　must　penetrate　inwards。　　　Voice　then　is　the　impact　of　the　inbreathed　air　against　the　'windpipe'；　and　the　agent　that　produces　the　impact　is　the　soul　resident　in　these　parts　of　the　body。　Not　every　sound；　as　we　said；　made　by　an　animal　is　voice　（even　with　the　tongue　we　may　merely　make　a　sound　which　is　not　voice；　or　without　the　tongue　as　in　coughing）；　what　produces　the　impact　must　have　soul　in　it　and　must　be　accompanied　by　an　act　of　imagination；　for　voice　is　a　sound　with　a　meaning；　and　is　not　merely　the　result　of　any　impact　of　the　breath　as　in　coughing；　in　voice　the　breath　in　the　windpipe　is　used　as　an　instrument　to　knock　with　against　the　walls　of　the　windpipe。　This　is　confirmed　by　our　inability　to　speak　when　we　are　breathing　either　out　or　in…we　can　only　do　so　by　holding　our　breath；　we　make　the　movements　with　the　breath　so　checked。　It　is　clear　also　why　fish　are　voiceless；　they　have　no　windpipe。　And　they　have　no　windpipe　because　they　do　not　breathe　or　take　in　air。　Why　they　do　not　is　a　question　belonging　to　another　inquiry。　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　9
  Smell　and　its　object　are　much　less　easy　to　determine　than　what　we　have　hitherto　discussed；　the　distinguishing　characteristic　of　the　object　of　smell　is　less　obvious　than　those　of　sound　or　colour。　The　ground　of　this　is　that　our　power　of　smell　is　less　discriminating　and　in　general　inferior　to　that　of　many　species　of　animals；　men　have　a　poor　sense　of　smell　and　our　apprehension　of　its　proper　objects　is　inseparably　bound　up　with　and　so　confused　by　pleasure　and　pain；　which　shows　that　in　us　the　organ　is　inaccurate。　It　is　probable　that　there　is　a　parallel　failure　in　the　perception　of　colour　by　animals　that　have　hard　eyes：　probably　they　discriminate　differences　of　colour　only　by　the　presence　or　absence　of　what　excites　fear；　and　that　it　is　thus　that　human　beings　distinguish　smells。　It　seems　that　there　is　an　analogy　between　smell　and　taste；　and　that　the　species　of　tastes　run　parallel　to　those　of　smells…the　only　difference　being　that　our　sense　of　taste　is　more　discriminating　than　our　sense　of　smell；　because　the　former　is　a　modification　of　touch；　which　reaches　in　man　the　maximum　of　discriminative　accuracy。　While　in　respect　of　all　the　other　senses　we　fall　below　many　species　of　animals；　in　respect　of　touch　we　far　excel　all　other　species　in　exactness　of　discrimination。　That　is　why　man　is　the　most　intelligent　of　all　animals。　This　is　confirmed　by　the　fact　that　it　is　to　differences　in　the　organ　of　touch　and　to　nothing　else　that　the　differences　between　man　and　man　in　respect　of　natural　endowment　are　due；　men　whose　flesh　is　hard　are　ill…endowed　by　nature；　men　whose　flesh　is　soft；　wellendowed。　　　As　flavours　may　be　divided　into　（a）　sweet；　（b）　bitter；　so　with　smells。　In　some　things　the　flavour　and　the　smell　have　the　same　quality；　i。e。　both　are　sweet　or　both　bitter；　in　others　they　diverge。　Similarly　a　smell；　like　a　flavour；　may　be　pungent；　astringent；　acid；　or　succulent。　But；　as　we　said；　because　smells　are　much　less　easy　to　discriminate　than　flavours；　the　names　of　these　varieties　are　applied　to　smells　only　metaphorically；　for　example　'sweet'　is　extended　from　the　taste　to　the　smell　of　saffron　or　honey；　'pungent'　to　that　of　thyme；　and　so　on。　　　In　the　same　sense　in　which　hearing　has　for　its　object　both　the　audible　and　the　inaudible；　sight　both　the　visible　and　the　invisible；　smell　has　for　its　object　both　the　odorous　and　the　inodorous。　'Inodorous'　may　be　either　（a）　what　has　no　smell　at　all；　or　（b）　what　has　a　small　or　feeble　smell。　The　same　ambiguity　lurks　in　the　word　'tasteless'。　　　Smelling；　like　the　operation　of　the　senses　previously　examined；　takes　place　through　a　medium；　i。e。　through　air　or　water…I　add　water；　because　water…animals　too　（both　sanguineous　and　non…sanguineous）　seem　to　smell　just　as　much　as　land…animals；　at　any　rate　some　of　them　make　directly　for　their　food　from　a　distance　if　it　has　any　scent。　That　is　why　the　following　facts　constitute　a　problem　for　us。　All　animals　smell　in　the　same　way；　but　man　smells　only　when　he　inhales；　if　he　exhales　or　holds　his　breath；　he　ceases　to　smell；　no　difference　being　made　whether　the　odorous　object　is　distant　or　near；　or　even　placed　inside　the　nose　and　actually　on　the　wall　of　the　nostril；　it　is　a　disability　common　to　all　the　senses　not　to　perceive　what　is　in　immediate　contact　with　the　organ　of　sense；　but　our　failure　to　apprehend　what　is　odorous　without　the　help　of　inhalation　is　peculiar　（the　fact　is　obvious　on　making　the　experiment）。　Now　since　bloodless　animals　do　not　breathe；　they　must；　it　might　be　argued；　have　some　novel　sense　not　reckoned　among　the　usual　five。　Our　reply　must　be　that　this　is　impossible；　since　it　is　scent　that　is　perceived；　a　sense　that　apprehends　what　is　odorous　and　what　has　a　good　or　bad　odour　cannot　be　anything　but　smell。　Further；　they　are　observed　to　be　deleteriously　effected　by　the　same　strong　odours　as　man　is；　e。g。　bitumen；　sulphur；　and　the　like。　These　animals　must　be　able　to　smell　without　being　able　to　breathe。　The　probable　explanation　is　that　in　man　the　organ　of　smell　has　a　certain　superiority　over　that　in　all　other　animals　just　as　his　eyes　have　over　those　of　hard…eyed　animals。　Man's　eyes　have　in　the　eyelids　a　kind　of　shelter　or　envelope；　which　must　be　shifted　or　drawn　back　in　order　that　we　may　see；　while　hardeyed　animals　have　nothing　of　the　kind；　but　at　once　see　whatever　presents　itself　in　the　transparent　medium。　Similarly　in　certain　species　of　animals　the　organ　of　smell　is　like　the　eye　of　hard…eyed　animals；　uncurtained；　while　in　others　which　take　in　air　it　probably　has　a　curtain　over　it；　which　is　drawn　back　in　inhalation；　owing　to　the　dilating　of　the　veins　or　pores。　That　explains　also　why　such　animals　cannot　smell　under　water；　to　smell　they　must　first　inhale；　and　that　they　cannot　do　under　water。　　　Smells　come　from　what　is　dry　as　flavours　from　what　is　moist。　Consequently　the　organ　of　smell　is　potentially　dry。
  10
  What　can　be　tasted　is　always　something　that　can　be　touched；　and　just　for　that　reason　it　cannot　be　perceived　through　an　interposed　foreign　body；　for　touch　means　the　absence　of　any　intervening　body。　Further；　the　flavoured　and　tasteable　body　is　suspended　in　a　liquid　matter；　and　this　is　tangible。　Hence；　if　we　lived　in　water；　we　should　perceive　a　sweet　object　introduced　into　the　water；　but　the　water　would　not　be　the　medium　through　which　we　perceived；　our　perception　would　be　due　to　the　solution　of　the　sweet　substance　in　what　we　imbibed；　just　as　if　it　were　mixed　with　some　drink。　There　is　no　parallel　here　to　the　perception　of　colour；　which　is　due　neither　to　any　blending　of　anything　with　anything；　nor　to　any　efflux　of　anything　from　anything。　In　the　case　of　taste；　there　is　nothing　corresponding　to　the　medium　in　the　case　of　the　senses　previously　discussed；　but　as　the　object　of　sight　is　colour；　so　the　object　of　taste　is　flavour。　But　nothing　excites　a　perception　of　flavour　without　the　help　of　liquid；　what　acts　upon　the　sense　of　taste　must　be　either　actually　or　potentially　liquid　like　what　is　saline；　it　must　be　both　（a）　itself　easily　dissolved；　and　（b）　capable　of　dissolving　along　with　itself　the　tongue。　Taste　apprehends　both　（a）　what　has　taste　and　（b）　what　has　no　taste；　if　we　mean　by　（b）　what　has　only　a　slight　or　feeble　flavour　or　what　tends　to　destroy　the　sense　of　taste。　In　this　it　is　exactly　parallel　to　sight；　which　apprehends　both　what　is　visible　and　what　is　invisible　（for　darkness　is　invisible　and　yet　is　discriminated　by　sight；　so　is；　in　a　different　way；　what　is　over　brilliant）；　and　to　hearing；　which　apprehends　both　sound　and　silence；　of　which　the　one　is　audible　and　the　other　inaudible；　and　also　over…loud　sound。　This　corresponds　in　the　case　of　hearing　to　over…bright　light　in　the　case　of　sight。　As　a　faint　sound　is　'inaudible'；　so　in　a　sense　is　a　loud　or　violent　sound。　The　word　'invisible'　and　similar　privative　terms　cover　not　only　（a）　what　is　simply　without　some　power；　but　also　（b）　what　is　adapted　by　nature　to　have　it　but　has　not　it　or　has　it　only　in　a　very　low　degree；　as　when　we　say　that　a　species　of　swallow　is　'footless'　or　that　a　variety　of　fruit　is　'stoneless'。　So　too　taste　has　as　its　object　both　what　can　be　tasted　and　the　tasteless…the　latter　in　the　sense　of　what　has　little　flavour　or　a　bad　flavour　or　one　destructive　of　taste。　The　difference　between　what　is　tasteless　and　what　is　not　seems　to　rest　ultimately　on　that　between　what　is　drinkable　and　what　is　undrinkable　both　are　tasteable；　but　the　latter　is　bad　and　tends　to　destroy　taste；　while　the　former　is　the　normal　stimulus　of　taste。　What　is　drinkable　is　the　common　object　of　both　touch　and　taste。　　　Since　what　can　be　tasted　is　liquid；　the　organ　for　its　perception　cannot　be　either　（a）　actually　liquid　or　（b）　incapable　of　becoming　liquid。　Tasting　means　a　being　affected　by　what　can　be　tasted　as　such；　hence　the　organ　of　taste　must　be　liquefied；　and　so　to　start　with　must　be　non…liquid　but　capable　of　liquefact