LECTIO NINETEEN

             § 479. Having dealt with the visible and the audible, the Philosopher now considers smell and its object. His treatment has two parts: he first examines this object as such, and then at 'Smelling also' the manner in which it impinges upon the sense. And as to the object as such, having considered it in itself, he turns, at 'Furthermore, as hearing', to consider a certain odourless object which falls within the range of smell. The former consideration again subdivides: first, he shows the difficulty of reaching definite conclusions about smell; secondly, he explains how we can come to know about the odorous, at 'For it seems that smell has an analogy'.

             First then he observes that it is harder to reach conclusions about smell and its object than about the sense-objects discussed hitherto, the audible and the visible. For what odour is is not as clear to us as what sound is, or the visible, or light, or other things of that sort.

             § 480. The reason, he says, is that our sense of smell is not so strong that we can distinctly and unerringly discern its object; for this sense is weaker in us than in many other animals; the reason being that, as the sense-organ corresponds to the sense-object, and as smell is produced by the warm and dry, therefore a good organ of smell will be predominantly a warm, dry organ. Now the brain of man, close to which lies the organ of smell, is, as the Philosopher says in the De Animalibus, larger in proportion to his body than that of any other animal; and since the brain itself is cold and moist, the human sense of smell is proportionately the less. Man smells weakly--indeed only what is strongly odorous and causes pleasure or disgust; and this because his sense of smell is lacking in a keen and exact discernment of its object. Hence one may reasonably opine that human beings stand with respect to odours in the same case as hard-eyed animals, such as locusts and certain types of fish stand with respect to colours; for these animals, on account of their weak vision and ill-disposed organs, see only what is very obviously visible and as such is apt to frighten them, or the contrary.

             § 481. Then at 'For it seems that. . .', he shows how differences of odour are made known to us. First, he shows how differences of odour are brought home to us by comparison with differences of taste. Secondly, he shows how differences of odour correspond to differences of taste, at 'As some flavours'.

             First, then, he remarks that the sense of smell in man seems to have some relation and correspondence to taste; and, likewise, the varieties of flavour (i.e. savour) to those of odour. Now things hidden become known through what is more evident. Since, then, the varieties of flavour are clearly evident to us, those of smell, which are not so, but which have a certain affinity to those of flavour, are brought home to us through this resemblance.

             § 482. Now the varieties of flavour are especially evident to us because man has a more acute sense of taste than other animals, taste being a modality of touch and touch being possessed by man at a far higher degree of precision than by any other animal; although in respect of the other senses man falls short of some animals. For certain animals see and hear and smell better than man: but the touch of man is far superior to that of other animals in exactitude of apprehension.

             § 483. This pre-eminence of touch in man is the reason why man is the wisest of animals; moreover, among men it is in virtue of fineness of touch, and not of any other sense, that we discriminate the mentally gifted from the rest. Those whose bodily constitution is tough, and whose sense of touch is therefore poor, are slow of intellect; whilst those of a delicately balanced constitution with, in consequence, a fine sense of touch are mentally acute. This too is why the other animals have flesh of a coarser texture than man.

             § 484. Yet it might seem that mental capacity corresponded rather to excellence of sight than of touch, for sight is the more spiritual sense, and reveals better the differences between things. Still, there are two reasons for maintaining that excellence of mind is proportionate to fineness of touch. In the first place touch is the basis of sensitivity as a whole; for obviously the organ of touch pervades the whole body, so that the organ of each of the other senses is also an organ of touch, and the sense of touch by itself constitutes a being as sensitive. Therefore the finer one's sense of touch, the better, strictly speaking, is one's sensitive nature as a whole, and consequently the higher one's intellectual capacity. For a fine sensitivity is a disposition to a fine intelligence. But an exceptionally good hearing or sight does not imply that the sensitivity as a whole is finer, but only that it is so in one respect.

             § 485. The other reason is that a fine touch is an effect of a good bodily constitution or temperament. For as the organ of touch is itself necessarily endowed with tangible qualities (being composed of the elements) it needs to be in a condition of potency to extremes of the tangible at least by itself constituting a mean between them. Now nobility of soul follows upon a well-balanced physical constitution; because forms are proportionate to their matter. It follows that those whose touch is delicate are so much the nobler in nature and the more intelligent.

             § 486. Another question that arises is why the differentiations of odour are named after those of taste, if it is touch that is the most exact of the senses. I answer that both the odorous and the tasty are caused to be so by some special combination of elemental qualities; consequently the former corresponds to the latter more than to the simple qualities which are the object of touch.

             § 487. Next, when he says 'As some flavours are sweet etc.', he explains how the kinds of odour correspond to the kinds of flavour or taste, observing that as we distinguish these as sweet or bitter, so do we also with odours. But notice that, while some things reveal a harmony of flavour and odour, that is to say, they are sweet in both, others on the contrary have an agreeable flavour but a disagreeable smell, or the converse.

             § 488. The reason for this is that flavour pertains to an aqueous liquid partially digested; and odour to a dry gaseous matter partially modified by the surrounding atmosphere. Now it sometimes happens that both substances, the subtle gas and the grosser liquid, are each combined in a nice proportion; and then both odour and flavour are pleasing. But if in one this balance is found, and not in the other, then the one will be pleasing but the other not so.

             And what has been said of sweet and bitter, the extremities in flavour, can be applied also to the sour, the pungent, i.e. astringent or harsh, the acid and the oily: these flavour-qualities can be transferred to the odorous.

             § 489. And although odours and flavours do not always and in all respects correspond, nevertheless because odours are, as I have said, only imperfectly distinct and evident, they are named after their resemblance to flavours; for on the whole there is a correspondence. Thus saffron and honey have both a sweet taste and a sweet smell, and thyme and suchlike have a pungent taste and smell; and so with other flavours and odours.

             § 490. Then, at 'Furthermore, as hearing', he shows how odourless things are perceptible to smell. As hearing, he says, is of the audible and inaudible, and sight of the visible and invisible (because opposites are known by one and the same faculty, and a lack only by means of what is lacking), so smell is of the odorous and the odourless. There are two senses of the term odourless: it can mean what has no smell at all, such as all simple (i.e. uncompounded) bodies, or what has a little or a faint smell. And the same is true of the tasty and the tasteless.

421b 8-422a 7

SMELL. HOW IT OCCURS

             SMELLING also takes place through a medium, which is either air or water. For aquatic animals seem also to perceive odours, both those with blood and those without, like animals that live in the air; for some of them traverse long distances for their food, being drawn to it by smell.§§ 491-5

             So there seems to be a difficulty. If operations of smell are of the same type, yet man smells by inhaling: when exhaling or holding his breath he smells nothing, neither from a distance, nor close at hand, not even if the object is placed inside the nose. (That a thing should be imperceptible when placed on the very organ of sensation, is indeed common to all, but to be unable to perceive without breathing is peculiar to man. This is evident to those who make the experiment). Since, then, bloodless animals do not breath, they would seem to have some other sense besides those which have been spoken of.§ 496

             But this is impossible, if it is odour they perceive. For the sense for odours, good odours or bad, is smell. Furthermore, they seem to be overcome by the same strong odours as man, such as asphalt, brimstone and the like. Therefore, even if they do not breathe, they must smell.§§ 497-8

             Now this sense seems to differ as between man and other animals, as human eyes differ from the hard eyes of some animals. The former have a covering or protection, the eyelids, and unless these are moved or withdrawn, one does not see. Hard-eyed animals have nothing like this; they see at once whatever happens to be present in the transparent medium. In the same way, then, the organ of smell is in some animals like an eye with no covering; in others, which inhale air, it has a covering that is withdrawn when they respire and so distend the veins and pores. And for this reason animals that breathe do not smell in water. For they must respire if they are to be affected by odour, and they cannot do this in a liquid.§ 499

             Odour is of dry things as savour of liquid; and the sense- organ of smell is such in potency.§ 500