Friendship for the good, and between the virtuous, is alone perfect; it is formed slowly, and has the requisites of permanence.

It occurs rarely (III.).

As regards the useful and the pleasant, the bad may be friends.

It may happen that two persons are mutually pleasant to each other, as lover and beloved; while this lasts, there is friendship.

It is only as respects the good, that there exists a permanent liking for the person.