Is Lily-Julie just a projection of Nicholas's own desires? Is reality just a projection of our own ideas? The former is one of the central questions in John Fowles's novel The Magus; the latter is the nucleus of constructivism. This study traces constructivist ideas and their transformation into narrative in The Magus. For long before constructivist theories were put forth, John Fowles confronts both the protagonist of his novel and the reader with the central constructivist theme: the construction of reality.