The ultimate metaphysical problem is the problem of being. One being with whom all of us are intimate is the entity we identify as “I”. What does the word “I” refer to? Does it refer to the body, the soul, or the mind? Those who reject dualism will assert that there is no distinction between the body and mind and that the soul doesn’t exist. Even in a non-dualistic system there is a differentiation between the mind and the body—the mind is regarded as an attribute or function of the brain. I can’t see how one can identify the essence of “I” without accepting some form of dualism. This dualism can be property dualism which envisages a universe composed of just one substance, the physical substance, which exhibits two types of properties: physical and mental.