Politian, Miscellanies 1.45:
There is an opinion long disseminated and accepted among everyone that Patroclus was younger than Achilles and was, as it were, loved by him as Hylas was by Hercules. Martial seems to make a nod to this when he says
The young friend was closer to Aeacides.
Therefore a dirty little verse from the Hermaphrodite was commonly applauded. Statius however claims in his Achilleid that they were both of equal age, writing,
There follows, joined then by a great love, Partoclus, and works as a rival to Achilles’ great deeds, equal in his pursuits and age, but much inferior in physical strength, and nevertheless set to see Troy with an equal fate.
Plato, however, argues something far different in the Symposium. For he declares that Achilles was much younger and that he was loved by Patroclus, being still beardless and not only more beautiful than Patroclus, but also than all the other heroes. Indeed, for that cause, he says, the gods loaded him with exceptional honors to send him off to the Blessed Isles, because he made such a big deal of his lover that he not only opted to die for him, but even chose to die for him rather than to grow old in his homeland.
Indeed, Plato criticizes Aeschylus for being a clown because he put forth the claim that Achilles was Patroclus’ lover and cited Homer as the authority for the ages of the two. If anyone would like the words of Homer to be shown to them, they may read them in the eleventh book of the Iliad in the character of Nestor with the orders which Menoetius used to send his son Patroclus to the war.