Parents, then, love their children as themselves (for what proceeds from them is as it were a second self when it is severed), but children love their parents as the source of their being, and brothers love each other because they proceed from the same source: for the identity of their relation to this source constitutes an identity between them; so that they say that they are of the same blood and stock, etc. And so they are in a way identical, though they are separate persons.

But friendship between brothers is greatly furthered by common nurture and similarity of age; for those of the same age naturally love one another, as the saying is, and those who are used to one another naturally make comrades of one another, so that the friendship of brothers comes to resemble that of comrades.

Cousins and other kinsfolk become attached to each other for the same reason⁠—I mean because they come of the same stock. But the attachment is more or less close according to the nearness or remoteness of the founder of the family.