This lecture introduces students to two broad theories of how the mind relates to the body. Dualism is the ubiquitous and intuitive feeling that our conscious mind is separate from our physical bodies, whereas Materialism is the idea that all of our mental states are caused by physical states of the brain. This lecture reviews arguments explaining why materialism has become the predominant theory of mind in psychology. This discussion is followed by a basic overview of the neurophysiology of the brain.