I suppose that the causality goes mind -> physical in an idealist veiwpoint, whereas in a materialist viewpoint phyiscal things cause mental things, and in a monist viewpoint mental and physical are two aspects of the same thing.

At least one of my friends claims to have some weak ability to alter physical reality by thinking (which is possible if physical reality is an illusion), which is interesting because he is otherwise a very intelligent scientist.

Also, believing that physical reality is an illusion is, like whoa man, its really deep.