In The Little White Bird, the J. M. Barrie novel in which Peter Pan first appears, Peter can fly because, like all babies, he was originally a bird. Barrie says that that Peter's age is "one week" and that, like all babies, he tried to escape from being a human. He affected his escape by going out the window, seeing the trees of Kensington Gardens across the way, and, forgetting "that he was now a little boy in a nightgown,...away he flew, right over the houses to the Gardens." It is Peter's belief that makes it possible to fly; Barrie writes that "the moment you doubt whether you can fly, you cease forever to be able to do it.

The Lost Boys are a different case. In Peter Pan and Wendy, the Lost Boys can fly, but unlike Peter, who is perpetually a child, the Lost Boys are human. When they return to London and are adopted by the Darlings, they become like normal human children and lose their ability to fly. This has more to do with a loss of belief, Barrie suggests, than any physical change. At first they were tied to their beds to prevent them from trying to escape and fly away; eventually, they lost the will to escape and also the power to fly.