I know that the unhappy are never pleasing, and that all naturally avoid the contagion of misery.
 Samuel Johnson, The History of Rasselas, Prince of Abissinia (1759). copy citation

Context

“She observed his backwardness, and commanded him to attend her. “You are not,” said she, “to confound impatience with resentment, or to suppose that I charge you with negligence because I repine at your unsuccessfulness. I do not much wonder at your absence. I know that the unhappy are never pleasing, and that all naturally avoid the contagion of misery. To hear complaints is wearisome alike to the wretched and the happy; for who would cloud by adventitious grief the short gleams of gaiety which life allows us, or who that is struggling under his own evils will add to them the miseries of another?” source