“ Mark how God ever brings like men together
2; “And thief knows thief and wolf his fellow wolf.”3And the natural philosophers even arrange the whole of nature in a system by assuming as a first principle that like goes to like, owing to which Empedocles4 said that the dog sits on the tiling because it is most like him.5Some people then give this account of a friend; but others say that opposite is dear to opposite, since it is what is loved and desired that is dear to everybody, and the dry does not desire the dry but the wet (whence the sayings—"Earth loveth rain,"6 and "In all things change is sweet—"7 change being transition to the opposite), whereas like hates like, for "Potter against potter has a grudge,"8 and animals that live on the same food are hostile to one another.  These opinions, therefore, are thus widely variant. One party thinks that the like is friend and the opposite foe—
“ For jackdaw by the side of jackdaw . . .
9and moreover adversaries are separated in locality, whereas friendship seems to bring men together. The other party say that opposites are friends, and Heracleitus10 rebukes the poet who wrote—
“ The less is rooted enemy to the more
For ever, and begins the day of hate,
for, he says, there would be no harmony without high and low notes, and no animals without male and female, which are opposites.These, then, are two opinions about friendship, and being so widely separated they are too general11; but there are others that are closer together and more akin to the facts of observation. Some persons think that it is not possible for bad men to be friends, but only for the good. Others think it strange that mothers should not love their own children (and maternal affection we see existing even among animals—at least, animals choose to die for their young). Others hold that only what is useful is a friend, the proof being that all men actually do pursue the useful, and discard what is useless even in their own persons (as the old Socrates12 used to say, instancing spittle, hair and nails), and that we throw away even parts of the body that are of no use, and finally the body itself,
“ Would strife might perish out of heaven and earth,