is the source of knowledge, but the reason of mankind is the norm by which all authority is judged." Sergei N. Shushkov has challenged the dominant strains of Eriugena scholarship in pointing out these key points regarding the approach to the structure, internal progression and purpose of the De Divisione Naturae: Rather than the specific divisions of Nature, the modes of interpreting being and non-being are to the true constitutive subject-matter of each book of the Periphyseon (hence, of the five parts of his system, yet four divisions). The fourfold division of Nature is to be interpreted not as a basic structure of the system offered by Eriugena, but as a means of introducing dialectic to the body of theology through discourse and negation of St. Augustine's specific metaphysical hierarchy, indicating the way of resolution of the cardinally theological contradiction (God does and does not create at the same time). Thus one should not associate Eriugena's work with exploration of the division of God's Nature but rather reinterpret it as an immense anti-division project to be understood as an important turn in the history of Christian thought entirely focused on the truth of God's unity and perfection, and the lived human life assenting to it. The fourfold divisions of nature The Latin title refers to these four divisions of nature: Creating and not created. Created and creating. Created and not creating. Not creating and not created. The first is God as the ground or origin of all things; the second, Platonic ideas or forms as logoi, following St. Maximus and Augustinian exemplarism; the third, corporeal world of phenomena and formed matter world; and the last is God as the final end or goal of all things, and that into which the world of created things ultimately returns. The third division is the dialectical counterpart to the first, the fourth to the second. The inspiration of this division comes from Augustine's City of God, "The cause of things, therefore which makes but is not made, is God; but all other causes both make and are made." The first and fourth divisions are to be understood of God, regarded alternately as the efficient and sustaining cause of all as dependent upon Him, and the teleological end of all: Let us then make an “analytical” or regressive collection of each of the two pairs of the four forms we have mentioned so as