Kant's Metaphysical Foundations of Natural Science, in which is found his most sustained attempt at a practical application of his principles to the phenomenon of matter in motion, is here subjected to critical analysis by Ryall. It is again established, against Kant, that the Copernican world-view presupposes for its vindication, not an "empirical space" and "relative" motion but a physical space and absolute motion; which presupposition, however, is adequately inferred on the basis of our experience itself. Because it is demonstrated that the observing subject is incapable of 'sensibly representing" the true motions in question, Ryall's assessment of the Metaphysical Foundations, which was Kant's last best chance to demonstrate that this can indeed be achieved, brings the negative part of his thesis to a close.