Physics is the general analysis of nature, conducted in order to understand how the universe behaves. On the other hand, the study of meteorological weather patterns or human behavior is only of interest to humans themselves. The point is that having a perspective on the world is a psychological state. Therefore, the special sciences presuppose the existence of minds which can have these states. If one is to avoid ontological dualism, then the mind that "has" a perspective must be part of the physical reality to which it "applies" its perspective. If this is the case, then in order to perceive the physical world as psychological, the mind must have a perspective on the physical. This, in turn, presupposes the existence of mind.