The Trumpet of the Swan, by E.B. White
Do not let an unnatural sadness settle over you, Louis,” said the cob. “Swans must be cheerful, not sad; graceful, not awkward; brave, not cowardly. Remember that the world is full of youngsters who have some sort of handicap that they must overcome. You apparently have a speech defect. I am sure you will overcome it, in time. There may even be some slight advantage, at your age, in not being able to say anything. It compels you to be a good listener. The world is full of talkers, but it is rare to find anyone who listens. And I assure you that you can pick up more information when you are listening than when you are talking.