 Schopenhauer’s PhD dissertation of 1813, The Fourfold Root of the Principle of Sufficient Reason, examines what many philosophers have recognized as an innate tendency to assume that in principle, the universe is a thoroughly understandable place. His dissertation, in effect, critically examines the disposition to assume that what is real is what is rational. A century earlier, G.W. Leibniz (1646–1716) had defined the principle of this assumption – the principle of sufficient reason – in his Monadology (1714) as that which requires us to acknowledge that there is no fact or truth that lacks a sufficient reason why it should be so, and not otherwise.