On Sense And The Sensible   

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.