William Chase Greene in Harvard Studies in Classical Philology
"Even when the world was young, the philosopher had the reputation of being an unpractical star-gazer who had little in common with his fellowmen. Search the indices of Plato, and you will find no imputation of wit, humor, or satire. The uninitiated will suppose that Plato was as solemn as the rest of the tribe. Yet several clues might save us at the start from so capital an error."
(Thanks to Jay Gold)