Philo Judaeus De Vita Contemplativa 57

Now of the banquets among the Greeks the two most celebrated and most remarkable are those at which Socrates also was present, the one in the house of Callias, when, after Autolycus had gained the crown of victory, he gave a feast in honour of the event, and the other in the house of Agathon, which was thought worthy of being commemorated by men who were imbued with the true spirit of philosophy both in their dispositions and in their discourses, Plato and Xenophon, for they recorded them as events worthy to be had in perpetual recollection, looking upon it that future generations would take them as models for a well managed arrangement of future banquets;