Calpurnia

I am quite sure that a couple of years ago I came across an anecdote in some book or other, online, about an ancient Greek philosopher and a young man. The story was that the philosopher who was "a member of the gay community" at least when his wife wasn't looking, lured or paid the young man to let him enjoy him then when the deed was done and he got up to leave, he noticed that the young man had taken his new and expensive cloak, leaving him to return to the town in a cheap and inferior one. I have searched and searched for this again but completely failed to track it down. Can anyone help me?