The book sees to show that the present discussion so unfolds as to show that ultimately Reality's inherent impetus to lawful order serves also to account for its existence. The ultimate explanation of its order is as something that also provides for its reason for being. Step by step, a train of thought unfolds to indicate that Reality both exists and has the nature it does for good reason, and specifically because this is somehow for the best. Such an approach goes back to the Platonism of classical antiquity. Many difficulties lie in the way of its acceptance. But is it, in the final analysis, the theory that works here takes the form of a Neo-Platonism of sorts. Or if reality has any rational explanation at all, it is one that will have to proceed along these lines, based upon rationality itself. An underlying theme that runs throughout the present elaboration of metaphysics is the dialectic of interaction between descriptive facts on the one hand and normative ideals on the other. On such a view, it is a salient factor in metaphysics that reality as such is descriptively constituted as a potentially perfect system of knowledge even though we imperfect beings cannot get a more than an imperfectly secure cognitive grip on it. Accordingly, we can never hope to surmount the contrast between: - The metaphysical ideal of a perfected system of knowledge. - The imperfect realization of actuality that we can ever hope to achieve in practice.