Thus the universe is to be conceived as attaining the active self-expression of its own variety of opposites of its own freedom and its own necessity, of its own multiplicity and its own unity, of its own imperfection and its own perfection. All the opposites are elements in the nature of things, and are incorrigibly there. The concept of God is the way in which we understand this incredible fact that what cannot be, yet is.
Process and Reality: An Essay in Cosmology (1929)