the part we know, but the process of reconstruction must remain approximative. Our position forbids the possibility of a final system. Instead, therefore, of constantly beginning afresh in speculation, it should be our duty to attach ourselves to what may be considered the permanent results of historic developments. The classical expression of these results Trendelenburg finds mainly in the Platonico-Aristotelian system. The philosophical question is stated thus: How are thought and being united in knowledge? How does thought get at being? And how does being enter into thought? Proceeding on the principle that like can only be known by like, Trendelenburg next reaches a doctrine peculiar to himself (though based upon Aristotle) that plays a central part in his speculations. Motion is the fundamental fact common to being and thought; the actual motion of the external world has its counterpart in the constructive motion involved in every instance of perception or thought. From motion he proceeds to deduce time, space and the categories of mechanics and natural science. These, being thus derived, are at once subjective and objective in their scope. It is true that matter can never be completely resolved into motion, but the irreducible remainder may be treated, like Aristotle, as an abstraction we asymptotically approach but never reach. The facts of existence, however, are not adequately explained by the mechanical categories. The ultimate interpretation of the universe can only be found in the higher category of End or final cause. Here Trendelenburg finds the dividing line, between philosophical systems. On the one side stand those that acknowledge none but efficient causes, which make force prior to thought, and explain the universe, as it were, a tergo ("from the back"). This may be called, typically, Democritism. On the other side stands the organic or teleological view of the world, which interprets the parts through the idea of the whole, and sees in the efficient causes only the vehicle of ideal ends. This may be called in a wide sense Platonism. Systems like Spinozism, which seem to form a third class, neither sacrificing force to thought nor thought to force, yet by their denial of final causes inevitably fall back into the Democritic or essentially materialistic standpoint, leaving us with the great antagonism of the mechanical and the organic systems of philosophy. The latter view, which receives its first support in the facts of life, or organic nature as