Marcel Duchamp’s three-quarter-length portrait of Raymond Dumouchel, a childhood friend who was studying medicine, is remarkable for its non-naturalistic colors, especially the vivid pink halo that surrounds the hand and upper body and strong contrasts with the composition’s green tones. The halo can be interpreted in relation to X-rays, which, since their discovery a quarter-century before, had gripped the public imagination as a tool for seeing past the surface of ordinary reality. But Duchamp was also alert to an occult interpretation of modern science which understood X-rays as a way of registering supernatural forces beyond the boundaries of the knowable. Either way, the portrait stands as an early expression of his lifelong belief that artists should endeavor to go beyond direct visual description and emphasize the mental side of art-making instead.