Lecture 12 — The species of odors

There are two species of the odorous. For it is not the case that, as some say, there are no species of the odorous; there are. But the ways in which there are and are not must be determined.

One kind of odor is ordered according to flavors, as was said. These contain the pleasant and unpleasant accidentally. For because odor is an affection of nourishment, these odors are pleasant to those that have an appetite. But to those that are full and not in need, neither the odors nor the food that has the odors is pleasant. Therefore, as we said, these contain the pleasant and unpleasant accidentally, and for this reason they are common objects for all animals.

But some odors, such as those of flowers, are pleasant of themselves.

For they do not follow from food with respect to more and less. And they do not contribute anything to desire, but rather the contrary. For what Thracius said in criticism of Euripides is true: when you cook lentils, you do not pour on ointment.

And those who do mix such virtues into drinks do violence to pleasure by the practice until it becomes pleasant to two senses, in the way that one thing is pleasant to one.

This species of the odorous, then, is proper to the human being. But the kind that is ordered according to flavors is also an object for other animals, as was said above. And because the latter contains the pleasant accidentally, its species are divided according to flavors. But the former is not, because its very nature is, of itself, pleasant or unpleasant.

Now the cause of this kind of odor being proper to the human being is the coolness around his brain. For the brain is cool by nature. And the blood around it in narrow veins is fine and pure, but easily cooled. For this reason, fumes from food, when cooled because of the coolness of this region, cause rheumatic illnesses in human beings. This kind of odor is produced as an aid to health, for it has no other function than this, and this it clearly has.

The odor that is pleasant because of food, dry or moist, is often unhealthy. But that which is pleasant because of odor that is of itself odorous, whatever it may be, is always useful, so to speak.

For this reason it is done by breathing—not in all animals, but in human beings and those that have blood, such as quadrupeds and those which participate more in the nature of air.

When odors rise to the brain because of the lightness of the heat in them, this area is healthier. For odor by nature has the power of heat. Nature uses breathing for two things: actively as an aid to the chest, and adventitiously for odor. For in breathing one causes movement through the nostrils as through a passageway. This genus of odor is proper to the nature of the human being because he has a bigger and moister brain in proportion to his size than do the other animals. And for this reason the human being, alone among the animals so to speak, senses and enjoys the odors of flowers and such things: for their heat and movement are commensurate with the hyperbole in this area of coolness and moistness.

To the other animals that have lungs, nature gave sensation of the other kind of odor by means of breathing, so as not to make two sensitive parts. For this is sufficient. Just as it is by breathing that human beings have sensation of both kinds of the odorous, in the same way these animals have sensation of just one kind.

177. There are two species of the odorous (443b16), etc. After the Philosopher has determined the generation and nature of odor, here he determines the species of odors. On this point, he does two things.

First, he determines the various species of odor.

Second, he determines the modes of smelling, where he says for this reason (444a19; [187]).

On the first point, he does three things.

First, he proposes that there are species of odor.

Second, he determines the species of odor by correspondence with species of flavor, where he says one kind of odor (443b19; [178]).

Third, he determines the species belonging to odor of itself, where he says but some odors (443b26; [180]).

Accordingly, he first says that there are two species of the odorous, one by correspondence with flavors, the other pertaining to odor in itself. For what some say, that the odorous does not have species, is false, for it does. But we have to determine the ways in which it does and does not have species.

It is possible to determine species of odors by agreement with species of flavors, as was said above. (1.5, 443b6–16, cf. ch. 11, nn. 162, 174–76.) But the species of odor in itself are determined only by reference to the different kinds of odorous things, as when we say that the odors of roses, violets, and other such things are different. It is in these odors that the pleasant and the unpleasant are discerned.

178. Then, when he says one kind of odor (443b19), he determines about the species of odors that follow from the species of flavors.

He says that among odorous things, one kind is ordered according to the species of flavor, as was said above, and so the pleasant and unpleasant are in them accidentally, that is, not inasmuch as they have odor, but inasmuch as their odor indicates nourishment. For odor is an affection of nourishment, as flavor also is: for an animal discerns appropriate nourishment from a distance by means of odor, as it discerns appropriate nourishment taken in by means of flavor. And so these odors are not pleasant to animals that are full and not in need of food, just as neither is food that has these odors pleasant to them; but it is pleasant to animals that have an appetite for food—that is, ones that are thirsty or hungry—just as food or drink is also desirable to them. Hence it is clear that this kind of odorous contains the pleasant and unpleasant accidentally—that is, because of nourishment—as was said (443b21).

179. And because nourishment is common to all animals, all animals perceive these odors. But the all must be understood with reference to animals that have forward movement, and have to seek food from a distance by means of odor; in the case of immobile animals, taste and touch suffice for discerning suitability of food.

180. Then, when he says but some odors (443b26), he determines the per se species of odor.

First, he presents these species of odor.

Second, he shows which animals perceive them, where he says this species of the odorous (444a3; [184]).

On the first point, he does three things.

First, he presents what he intends.

Second, he proves the proposal, where he says for they do not follow (443b28; [181]).

Third, he eliminates an objection to the contrary, where he says and those who do mix (443b31; [183]).

Accordingly, he first says that some odors are pleasant of their very selves, that is, not in relation to food, and this is said to be the case with the odors of flowers.

181. Then, when he says for they do not follow (443b28), he proves that such odors are of themselves pleasant. This is because they are not related to food as a consequence of it, that is, such that animals with an appetite for food take more pleasure in these odors, and animals that are full less pleasure. Also, such odors do not contribute anything to desire for food in the way that the odors discussed above provoke an appetite for food. Rather the contrary occurs: food is made unpleasant by being mixed with things that have this kind of odor, because often what smells good inasmuch as it has this kind of odor, nevertheless has a bad taste.

182. To confirm this he introduces a saying of a certain comic poet named Thracius or Stratides, who, in criticism of another poet—namely Euripides, who devised very fastidiously prepared dishes—said: when you cook lentils, you do not pour on ointment—that is, sweet-smelling perfume; as if to say: “you shouldn’t add anything sweet-smelling to your relish.”

183. Then, when he says and those who do mix (443b31), he eliminates an objection that could be made because of the custom of some who do mix such things into food.

He answers by saying that those who do mix “virtues”—that is, odorous things—of this kind with food and drink do violence to natural pleasure by their custom in order to reach a point where one and the same thing is pleasant to two senses, namely taste and smell, whereas by nature one thing is pleasant to one sense.

184. Then when he says this species of the odorous (444a3), he shows by what animals such objects of smell are perceived. On this point, he does three things.

First, he presents what he intends.

Second, he gives a cause of what was said, where he says now the cause of this kind of odor (444a8; [185]).

Third, he excludes an objection, where he says the odor that is pleasant (444a16; [186]).

Accordingly, he first says that this species of the odorous that of itself pleases or displeases is proper to the human being, for the human being alone discerns such objects of smell and is pleased or displeased by them; hence, to this extent, the sense of smell is richer in the human being than in other animals. But odor that is coordinated with flavor is also an object for other animals, which have a more acute sense than does the human being for discerning such odors; and to this extent, as he said above, we have a worse sense of smell than do other animals. (Cf. ch. 8, n. 119.) And because those odors that are coordinated with flavors contain the pleasant accidentally—that is, in relation to food—their species are distinguished according to species of flavors, which is not the case with these odors that of their own nature contain the unpleasant or pleasant: rather, species of this kind of odor can be distinguished only with reference to odorous things, as was said. (Cf. n. 177.)

185. Then, when he says now the cause of this kind of odor (444a8), he gives the cause of what was said. He says that odor that is of itself pleasant is an object proper to the human being for moderating the coolness of his brain. For the human being has a larger brain, in relation to the size of his body, than do other animals. But the brain is by its nature cool, and the blood contained in fine veins around the brain is easily cooled. Because of this, vapors dissolved from food, rising upwards and being cooled because of the coolness of the region, sometimes become thick, which causes rheumatic illnesses in human beings. And so this kind of odor was given to human beings as an aid to health, to counter the excessive coolness of the brain. And if such odors sometimes cause headache, this is because they are not applied as they should be, but rather overheat the brain and cause too much evaporation. But if they are applied in the right way they contribute to health. And this clearly appears from their effect, although no other usefulness of such odor is apparent: for perception of such odors hardly serves intellect at all for investigating natures of things, whereas sight and hearing serve it very much, as was shown above. (1.1–2, 437a3–17; cf. ch. 1, nn. 27–32.)

186. Then, when he says the odor that is pleasant (444a16), he eliminates an objection. For someone might say that the other kind of object of smell, which is coordinated with flavor, would suffice for the remedy for health mentioned.

He answers that the kind of odor that is pleasant because of food often rather causes headache, because of either excessive moistness or excessive dryness. But the kind of odor that is in itself pleasant is always useful for health of its own nature. He adds so to speak because of the improper use.

187. Then, when he says for this reason (444a19), he concludes from what was said above to the appropriate modes of smelling.

First, in the human being and other breathing animals;

second, in non-breathing animals, where he says it is clear that the ones that do not breathe (444b7; [191]).

On the first point, he does three things.

First, he presents what he intends.

Second, he gives the cause proposed with reference to human beings where he says when odors rise to the brain (444a22; [188]);

and third with reference to other animals where he says to the other animals (444b2; [190]).

Accordingly, he first says that because odor is useful for moderating coolness of the brain, smelling is done by breathing—not in all animals, but in human beings and those that have blood, such as quadrupeds and birds, the latter of which also participate more in the nature of air, as their movement shows.

188. Then, when he says when odors rise to the brain (444a22), he shows the cause why odor is perceived by breathing with reference to human beings.

He says that odors rise to the brain because the heat of fire that releases odors gives them a lightness so that they move towards higher regions, and from this there follows a condition of health in the area of the brain. For odor has power to heat because of the heat of fire by which it is caused and released. Hence nature uses breathing for two things: actively—that is, principally—as an aid to the chest—that is, the breast; in other words, for cooling the heart’s heat—but adventitiously—that is, secondarily—for perceiving odor. For when the human being breathes, he moves air through the nostrils by drawing it in, and so causes odors to go to the organ of smell.

189. The reason why this genus of sensible objects is proper to human nature is because the human being has a bigger brain in proportion to his size, and a moister one, than do the other animals. And the reason why the human being alone among the animals senses and takes pleasure in the odors of flowers and other such things is that the heat of such odors and their movement towards the brain reduce the “hyperbole”—that is, the excess—of the brain’s coolness and moistness to the right measure. He added so to speak because other animals do flee bad odors inasmuch as they are destructive.

190. Then, when he says to the other animals (444b2), he gives the cause of smelling by breathing with reference to other animals.

He says that nature gave to animals with lungs, which are the only ones that breathe, sensation of the other kind of odor—that is, the one related to food—by means of breathing so as not to make two organs, one an organ of breathing and the other an organ of smelling. For the organ of breathing is sufficient also for smelling: just as for the human being it suffices for the two kinds of the odorous, so for other animals it suffices for the one alone.