Moreover, friendship is not only an indispensable, but also a beautiful or noble thing: for we commend those who love their friends, and to have many friends is thought to be a noble thing; and some even think that a good man is the same as a friend. 213

But there are not a few differences of opinion about the matter. Some hold that it is a kind of likeness, and that those who are like one another are friends, and this is the origin of “Like to like,” and “Birds of a feather flock together,” 214 and other similar sayings. Others, on the contrary, say that “two of a trade never agree.” 215

Others go deeper into these questions, and into the causes of the phenomena; Euripides, for instance says⁠—