§ viii. We ought not therefore to be too lavish with our virtue, binding it together and implicating it in various people's fortunes, but we ought to preserve our friendship for those who are worthy of it, and are capable of reciprocating it. For this is indeed the greatest argument against many friends that friendship is originated by similarity. For seeing that even the brutes can hardly be forced to mix with those that are unlike themselves, but crouch down, and show their dislike, and run away, while they mix freely with those that are akin to them and have a similar nature, and gently and gladly make friends with one another then, how is it possible that there should be friendship between people differing in characters and temperaments and ideas of life? For harmony on the harp or lyre is attained by notes in unison and not in unison, sharp and flat somehow or other producing concord, but in the harmony of friendship there must be no unlike, or uneven, or unequal element, but from all alike must come agreement in opinions and wishes and feeling, as if one soul were put into several bodies.
§ ix. What man then is so industrious, so changeable, and so versatile, as to be able to make himself like and adapt himself to many different persons, and not to laugh at the advice of Theognis, "Imitate the ingenuity of the polypus, that takes the colour of whatever stone it sticks to."22 And yet the changes in the polypus do not go deep but are only on the surface, which, from its thickness or thinness takes the impression of everything that approaches it, whereas friends endeavour to be like one another in character, and feeling, and language, and pursuits, and disposition. It requires a not very fortunate or very good Proteus,23 able by jugglery to assume various forms, to be frequently at the same time a student with the learned, and ready to try a fall with wrestlers, or to go a hunting with people fond of the chase, or to get drunk with tipplers, or to go a canvassing with politicians, having no fixed character of his own.24