Ancient Greeks mixed business with pleasure even as we do now. The original symposia were essentially drinking and game parties held after a dinner, and some Greek men were frat boy enough to leave behind an enduring legacy. Their antics have been
preserved for posterity in literature and on pottery shards.
As late as 1828, we find the word 'symposium' meant "A drinking together; a merry feast," with no other definitions added. In fact, the root 'po' is a variant of Greek for 'to drink.'
However, thanks to Plato, who injected lively philosophical discussion into the mix, today we equate the word with more intellectual pursuits.
Though the level of the symposia tells us a lot about the level of prevailing Greek culture at the time, Eschenburg contends that the parties were sometimes "literary feasts," and
evidence that [the Greeks] sought to avail themselves of every opportunity for the mutual interchange of literary acquisition, even in the hours of recreation and social amusement...
There were rules for directing the conduct and conversation at these repasts of the schools; as for example, a code or system of the kind was prepared by Xenocrates for the symposia of the Academy, and by Aristotle for those of the Lyceum. Banquets of this sort were also adopted as a mode of celebrating the birthday and memory of teachers and founders of the schools, or other distinguished persons.
The excellent dialogues of Plato and Xenophon ... furnish the reader with the best idea of this form of social entertainment among the wise men of Greece.
Source: Eschenburg