As with a lot of the details of Plato s life there is no contemporary source concerning this story It comes from Diodorus Library 15 7 Plutarch s Dion 4 5 and Diogenes Laertius Lives 13 18 21 In the link to the Diogenes translation the story begins under XIV but it s technically 13 18 of Diogenes text The three accounts differ in details and it s not known how true any of them are The incident is not I believe even mentioned in the notorious Seventh Letter which was written in or very near Plato s time We must keep in mind that in the centuries following great figures like Socrates Plato and Aristotle a lot of purportedly biographical information was simply made up out of whole cloth sometimes for the purpose of scandal sometimes just to fill in the gaps The ancient Greek scholars Kirk Raven Schofield speak of the great period of fictitious biography in the third and second centuries B C The Presocratic Philosophers Cambridge 1983 2nd edition p 81