We like to have other people participate in these activities with us because, as Plato said, “You learn more about a person in an hour of play than in a year of conversation.”
It’s been a while since I read the dialogues, and I couldn’t swear with certainty I’ve read every one, but that sure doesn’t ring any bells—and, more to the point, doesn’t really sound like the kind of thing Plato would say. The guy wrote dialogues, after all. A quick Google shows it cropping up on quotation pages, but never actually soured to a text, which makes me suspicious. Anyone?