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 new 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.
Epictetus, the Greek Stoic philosopher, had said, among other things, "It is difficulties that show what men are."
John Adams by David McCullough