The Prolegomena sets out the fundamental perception of the history of being now operative in consciousness. The center of the book is comprised of a two-part Reflection on the History of Being : Part I is an examination of the impact made on the shape of scientific philosophy by the fact of Christian faith. Aristotle, the sacra doctrina of Thomas Aquinas, and their relationship with the modern thinkers, Descartes, Kant, Hegel, and Kierkegaard are examined in this section. In Part II the history of the conception of time becomes the measure of a prospective analysis of the limits essential to the modern enterprise. Augustine, Leibniz, Husserl, and Heidegger become the major figures here, and there is a specific delineation of the relationship of the phenomenologists to Kierkegaard and Hegel.