These reflections lead directly to a problem that, since about the time of Descartes, has been at the center of all metaphysics: the relationship of mental to physical, of mind to body. In my opinion, this problem is one of those that owe their existence to a mistaken formulation of the issue. As a matter of fact, from the vantage point we now have gained, we see unfolded before us a world picture without those dark recesses in which the special difficulties, so feared under the label of the psychophysical problem, might find a hiding place. Viewed from this standpoint, the problem is solved even before it can be raised. This we shall now demonstrate. However, in order to set our minds completely at rest about the question, we must also uncover the source of the error that allowed the question of mind and body to become such a tormenting problem.