  Proclus himself often uses the term ‘theology’ in this metaphysical sense for the study of the first (‘divine’) principles of all things. His Elements of Theology can in fact be considered an introduction to his metaphysics.  The work is a concatenated demonstration of 217 propositions, which may be divided into two halves: the first 112 propositions establish the One, unity without any multiplicity, as the ultimate cause of reality and lay down basic metaphysical concepts/structures such as causality, participation, the relation of wholes to parts, infinity, and eternity. The second half deals with the three kinds of true causes within reality recognized by Proclus: gods (which he calls henads or “unities,” see below), intellects, and souls.  This elaborate metaphysical framework makes it possible for Proclus to develop a scientific theology, i.e., a demonstration of the procession and properties of the different classes of gods. In what follows we will only discuss some characteristic features of Proclus’ metaphysics (see further Steel 2011).