Plutarch, De amicorum multitudine
Goodwin, Ed.

And it is impossible any should be friends that resent not mutually the affronts and injuries offered unto either, and that do not hate alike and in common. They also who are enemies to yourself will presently suspect and hate your friend; nay, your other friends too will often envy, calumniate, and undermine him. Wherefore what the oracle foretold Timesias concerning his planting a colony, that an hive of bees should be changed into a nest of wasps, may not impertinently be applied to those who seek after a hive of friends, but light before they know it upon a wasps-nest of enemies.

[p. 472] Besides, we should do well to consider that the kindest affections of friends seldom compensate for the misfortunes that befall us from the malice of enemies. It is well known how Alexander treated the familiars of Philotas and Parmenio; Dionysius, those of Dion; Nero, those of Plautus; and Tiberius, those of Sejanus; all shared the same hard fate of being racked and tortured to death. For as the gold and riches Creon's daughter was adorned with could not secure the good old father from being consumed in her flames, endeavoring too officiously to rescue her; so not a few partake of the calamities and ruin of their friends, before they have reaped the least advantage from their prosperity; a misfortune to which philosophers and the bestnatured men are the most liable. This was the case of Theseus, who for the sake of his dear Pirithous shared his punishment, and was bound with him in the same eternal chains.¹ Thus in the plague of Athens, says Thucydides,² the most generous and virtuous citizens, while without regard to their own safety they visited their sick, frequently perished with their friends.