 Book One opens abruptly with the claim that “nature” (natura), “the general term for all things that are and all things that are not”, (I.441a), including both God and creation, is divided into four species. Echoing similar divisions in Augustine (De civitate Dei Bk. V. 9, PL 41: 151) and Marius Victorinus (Ad Candidum), nature’s four “divisions” or “species” are: that which creates and is not created (i.e., God); that which creates and is created (i.e., Primary Causes or Ideas); that which is created and does not create (i.e., Temporal Effects, created things); that which is neither created nor creates (i.e., non-being, nothingness). The first species of nature is God, “the cause of all things that are and that are not” (I.442b). There are several remarkable aspects of this division. First of all, division is defined by Eriugena in De praedestinatione as a branch of dialectic. Secondly, the four divisions are not strictly a hierarchy in the usual Neoplatonic sense where there are higher and lower orders, rather, as Eriugena will explain, the first and fourth divisions both refer to God as the Beginning and End of all things, and the second and third divisions may also be thought to express the unity of the cause-effect relation. Finally, the division is an attempt to show that nature is a dialectical coming together of being and non-being. Creation is normally understood as coming into being from non-being. God as creator is then a kind of transcendent non-being above the being of creation. These themes are rigorously discussed and disentangled throughout the dialogue.