When Kant in his investigation of the nature and validity of human knowledge in the Critique of Pure Reason (1781) undertook an examination of the nature of Space and Time as the starting point in the discussion, he struck the path which all fruitful philosophical investigation has followed since. Since Space and Time are the two ‘forms’ within which the whole system of life and nature unfolds itself to the human mind, and are at the same time the ‘warp and woof on which man elaborates his mental sense-picture of the world, an examination of these two sense-forms should be the self-evident starting point in any true cosmic philosophy. Yet it seems to have taken something more than a century for the full significance of Kant’s method to sink into the general philosophical consciousness, and it is only in our own time that its fruits have begun to mature. What strikes one in the philosophical writings of the present century, whether starting from mathematics, or science, or pure speculation, is the common assumption in all of them that some exposition of Space and Time must form the foundation of any adequate treatment of the nature of the world, the human mind, and the structure of human knowledge. The title of Professor Alexander’s book, Space, Time, and Deity (1920), is symbolic of the modern point of view.