Leonard Peikoff presents the hierarchical structure of the Objectivist metaphysics, deriving it step by step from the necessary logical order in which its principles must be grasped implicitly by a developing child. He concludes with a brief discussion of polemics, arguing that the two main errors in metaphysics are materialism and religion. He shows, in particular, in what way religion constitutes an all-out attack on every principle of the Objectivist metaphysics.