290. Connection of Theodicy with Metaphysics. -- Metaphysics, when dealing with corporeal substances -- the proper object of human knowledge (300) -- not only seizes their being, apart from matter (immaterial negatively, or by abstraction), but at the same time supplies us with a number of concepts and judgments which can be applied by analogy to what is immaterial positively, or of its very nature. Thus it is we can justify the employment of the term theology (rational) by Aristotle, the Arabians and some of the scholastics, as a synonym for metaphysics.

Already in Aristotle we find the great division of beings into two categories: on the one hand, those composed of act and potency, beings which, before actually possessing a perfection, exist in a condition deprived of that perfection; on the other hand, the Pure Act, free from all potentiality, God (45). The medieval scholastics took up these Aristotelian data, completed and enriched them and carried them into regions of thought unknown to Aristotle. Combining them with certain theories of the Fathers of the Church, especially of St Augustine, the scholastics built up a new theodicy which replaced the peripatetic notion of an immovable motor, wrapt up in self-contemplation, by the theory of the Ens "a Se," infinite in Its actuality.