Aristotle, Eudemian Ethics

[1236a] [1] And similarly also in the case of the spirit, the really pleasant things are not those pleasant to children and animals, but those pleasant to the adult; at least it is these that we prefer when we remember both. And as a child or animal stands to an adult human being, so the bad and foolish man stands to the good and wise man; and these take pleasure in things that correspond to their characters, and these are things good and fine.

Since therefore good is a term of more than one meaning (for we call one thing good because that is its essential nature, but another because it is serviceable and useful), and furthermore pleasant includes both what is absolutely pleasant and absolutely good and what is pleasant for somebody and apparently good—, as in the case of inanimate objects we may choose a thing and love it for each of these reasons, so also in the case of a human being, one man we love because of his character, and for goodness, another because he is serviceable and useful, another because he is pleasant, and for pleasure. And a man becomes a friend when while receiving affection he returns it, and when he and the other are in some way aware of this.

It follows, therefore, that there are three sorts of friendship, and that they are not all so termed in respect of one thing or as species of one genus, nor yet have they the same name entirely by accident. For all these uses of the term are related to one particular sort of friendship which is primary, like the term 'surgical'—and we speak of a surgical mind and a surgical hand and a surgical instrument and a surgical operation, [20] but we apply the term properly to that which is primarily so called. The primary is that of which the definition is implicit in the definition of all, for example a surgical instrument is an instrument that a surgeon would use, whereas the definition of the instrument is not implicit in that of surgeon. Therefore in every case people seek the primary, and because the universal is primary they assume that also the primary is universal; but this is untrue. Hence in the case of friendship, they cannot take account of all the observed facts. For as one definition does not fit, they think that the other kinds of friendship are not friendships at all; but really they are, although not in the same way, but when they find that the primary friendship does not fit, assuming that it would be universal if it really were primary, they say that the others are not friendships at all. But in reality there are many kinds of friendships: this was among the things said already,¹ as we have distinguished three senses of the term friendship—one sort has been defined as based on goodness, another on utility, another on pleasure.

Of these the one based on utility is assuredly the friendship of most people; for they love one another because they are useful, and in so far as they are and so, as says the proverb—“Glaucus, an ally is a friend, as long as he our battle fights,² and

“ Athens no longer knows Megara.
”

Fr. Eleg. Adespota 6 (Bergk)

On the other hand friendship based on pleasure is the friendship of the young, for they have a sense of what is pleasant; hence young people's friendship easily changes, for since their characters change as they grow up, their taste in pleasure also changes. But the friendship in conformity with goodness is the friendship of the best men.