In the justly famous scholium to the definitions, Newton has stated, with admirable precision, the doctrine of absolute space, time, and motion. Not being a skilled philosopher, he was unable to give grounds for his views, except an empirical argument derived from actual Dynamics. Leibniz, with an unrivalled philosophical equipment, controverted Newton's position in his letters against Clarke¹; and the victory, in the opinion of subsequent philosophers, rested wholly with Leibniz. Although it would seem that Kant, in the Transcendental Aesthetic inclines to absolute position in space, yet in the Metaphysische Anfangsgründe der Naturwissenschaft he quite definitely adopts the relational view. Not only other philosophers, but also men of science, have been nearly unanimous in rejecting absolute motion, the latter on the ground that it is not capable of being observed, and cannot therefore be a datum in an empirical study.