"Long before, on his rounds of Boston as a young lawyer, Adams had often heard a man with a fine voice singing behind the door of an obscure house. One day, curious to know who 'this cheerful mortal' might be, he had knocked at the door, to find a poor shoemaker with a large family living in a single room. Did he find it hard getting by, Adams had asked. 'Sometimes,' the man said. Adams ordered a pair of shoes. 'I had scarcely got out the door before he began to sing again like a nightingale,' Adams remembered. 'Which was the greatest philosopher? Epictetus or this shoemaker?' he would ask when telling the story."
David McCullough, John Adams, pages 570-571.