This book is based on the premise that the realm of being is meaningful to the extent that we are able to view it comprehensively. Our understanding, in its degree, depends on the breadth of our knowledge; for everything, as we shall see, tends to shed light on everything else. But the knowledge we have today, although far exceeding that of our predecessors, does not serve this purpose of illumination insofar as it remains unassembled, partitioned among the minds of the specialists who respectively represent the fields into which it is divided. ... In one of its aspects, this book is an exercise in perspective. As such, it will have much to say of the very small and the very large, of analysis and synthesis.--Preface.