Having examined Eriugena's concepts of human nature, mind, selfknowledge, and non-being, we are now in a position to interpret his most famous doctrine: the fourfold division of nature. This is the high point of Eriugena's physiologia (IV. 741c), his science of nature, which has intrigued commentators and yet has remained essentially uninterpreted. Eriugena is responding to a problem posed by his Neoplatonic sources, especially Dionysius and Maximus. The problem is the relation between God and His creation. Are God's ideas and willings part of Him and hence uncreated, or do they belong to the structure of created nature? Since there are no intermediaries between God and creation, according to Scripture, how can a Christian Neoplatonist resolve this problem? Eriugena's answer is to propose a fourfold division of nature, which includes a category of things which are both created and active in creating. This category is not a fixed ontological level or intermediary between God and creation, as we shall see.

In this chapter I shall argue that Eriugena's hierarchical scheme of nature is to be understood not as a fixed set of metaphysical levels or degrees of reality but, rather, as a set of theoriae, or mental acts of intellectual contemplation, which allow human subjectivity to enter into the infinite divine subjectivity and nothingness. The four divisions of nature exist only in so far as they are viewed by the mind and are resolved by the mind into acts of intellect.