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第6章

on sense and the sensible-第6章

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'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)

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