You can discover more about a person in an hour of play than in a year of conversation.

Plato (c.428-347 BC) Greek philosopher
(Spurious)

Frequently attributed to Plato, starting in the 1950s, but not found in his works. Earliest citation is as a Portuguese proverb, in A Polyglot of Foreign Proverbs, tr. Henry G. Bohn (1857): "Mais descobre huma hora de jogo, que hum anno de conversação." For more see here.