A lot of people use the quote and attribute it to Plato, but no source.
I have major doubts that he ever said it or wrote it.
Plato said,
"You can learn more about a person in an hour of play than in a life-time of conversation."
http://www.prairienet.org/woods/team.html
"You can learn more about an individual during an hour of play than in a year of conversation." - Plato
http://www.westex.net/leiza/challeng.htm
"You can discover more about a person in an hour of play than in a year of conversation." - Plato
http://www.friendsofrecoveryvt.org/news/novnews.html
We can learn more in an hour of play than we can in a lifetime of work. - Plato
http://www.funlosophy.com/intro.html