PETER: Because I heard father and mother talking of what I was to be when I became a man. I want always to be a little boy and to have fun; so I ran away to Kensington Gardens and lived a long time among the fairies.

J. M. Barrie (1860-1937) Scottish novelist and dramatist [James Matthew Barrie]

Peter Pan, Act 1 (1904, pub. 1928)
    (Source)

In Barrie's 1911 novelization, Peter and Wendy, ch. 3 "Come Away, Come Away!" this is rendered:

“It was because I heard father and mother,” he explained in a low voice, “talking about what I was to be when I became a man.” He was extraordinarily agitated now. “I don’t want ever to be a man,” he said with passion. “I want always to be a little boy and to have fun. So I ran away to Kensington Gardens and lived a long long time among the fairies.”