Royce distinguishes three approaches to natural theology. These lectures consist in an investigation of the third type, “the philosophy of religion,” which concerns itself with the metaphysics of Being and hence with God, while not depending on any special revelation.

In the first set of lectures, Royce expounds and defends a version of Absolute Idealism against its three rivals in the history of Western thought — Realism, Mysticism and Critical Rationalism (or Kantianism).

In the second set of lectures he investigates the relation between the Theory of Being advocated in the first, and the practical question of the meaning of the world in which human beings have to find a place. These lectures defend the claim that Royce's Theory of Being is not “a barren Absolute, which devours individuals,” but a place in which the aspirations of ethically free individuals can find their fulfilment and completion.