Metaphysics is the science that studies the conditions of the states of consciousness, asking three basic questions:

1. Are the states of consciousness, taken as a whole, dependent on the existence of the soul?

2. Are the states of consciousness relative to the material world and therefore dependent on the existence of bodies?

3. Are the states of consciousness relative to the principles of reason and therefore dependent on the existence of God?

But metaphysics is concerned not just with what the conditions of the states of consciousness are but with their nature as well. After studying whether the soul, bodies, and God exist, metaphysics then examines the essence, nature, and attributes of each.

So metaphysics asks three sets of questions:

1. Does the soul exist? What's its nature?

2. Do bodies exist? What's their nature?

3. Does God exist? What's His nature?

In our treatment of psychology, we already discussed the existence and nature of the external world. So all that's left to consider are questions about the soul and God. To answer these, we'll rely on the following method – one suggested to us by the way we've posed the problems of metaphysics. We'll try to determine whether the states of consciousness can exist on their own or whether they depend on certain external conditions. So we must begin by considering the states of consciousness themselves, setting our sights only on what's absolutely necessary to explain them.