The next phase of his development gave him a direct knowledge of Cartesian writings, and of other modern books beside, such as those of the atomist Gassendi. He was delighted with what he read, because of its fertility in the field of physics and mathematics; and for a short time he was an enthusiastic modern. But presently he became dissatisfied. The new systems did not go far enough, they were still scientifically inadequate. At the same time they went too far, and carried metaphysical paradox beyond the limits of human credulity. [13] There is no mystery about Leibniz's scientific objections to the new philosophers. If he condemned them here, it was on the basis of scientific thought and observation. Descartes's formulation of the laws of motion could, for example, be refuted by physical experiment; and if his general view of physical nature was bound up with it, then so much the worse for the Cartesian philosophy. But whence came Leibniz's more strictly metaphysical objections? Where had he learned that standard of metaphysical adequacy which showed up the inadequacy of the new metaphysicians? His own disciples might be satisfied to reply, that he learnt it from Reason herself; but the answer will not pass with us. Leibniz reasoned, indeed, but he did not reason from nowhere, nor would he have got anywhere if he had. His conception of metaphysical reason was what his early scholastic training had made it.