Harold's world is a blank slate through which he learns to draw his own experiences, with a purple crayon.
Toddler Harold draws his way into a moonlit stroll in a world of his own design. Unexpected events –a too scary dragon, a tumble into water and getting lost– combine to make his walk exciting yet ultimately it remains a matter of his own design. Although he, literally, draws every scenario with his purple crayon, and saves himself from their difficulties. it is clear that the metaphor is not about whim, so much as design.