As for the advice that one should proceed as if there were no books, no philosophical or philological doctrines in the world, its meaning is merely the necessity of ridding oneself of all prejudice, of all common habitual assumptions, of all accretions of memory and fancy, in order to attain "the state of pure understanding, empty of every particular form," which is necessary for the discovery and apprehension of any new truth. So far removed is this advice from the Cartesian or Malebranchian renunciation of learning and authority, that--to mention one fact only--in the very passage to which we have just referred we find the warning that the New Science presupposes a comprehensive and varied mass both of doctrine and of learning, the truths of which it takes over as already known, and uses them as terms in its new propositions. In a word, Vico in his new theory of knowledge became not more Cartesian but more Vician--more himself. Descartes seemed to him not even a serviceable path by which to attain proof of the possibility of constructing the science of mind by means of the mind. The true path was Vico's own criterion of truth, brought into relation with its author's observations made in the course of his historical studies. If we wish to look for precedents in the history of philosophy for Vico's theory of knowledge in its second form, the division between the two worlds of reality and the two spheres of consciousness, and the preference for moral as compared with natural studies, would lead us back to the position adopted by Socrates as against the "Physiologists" of his time, and the feeling of religious mystery which brought the Athenian philosopher to a standstill in face of the natural world and directed his efforts to the study of the mind of man. Again, as to the superior transparency of the moral sciences, as dealing with objects created by man himself, we might recall the Aristotelian division of the sciences into physical, treating of motion external to man, and practical and "poietic," which deal with man's own creations. The distinction passed into the philosophy of the schools: Thomas Aquinas speaks of nature as "an order which reason contemplates but does not create" (_ordo quem ratio considerat sed non facit_), and of the world of human activity as "an order which reason creates by contemplation" (_ordo quem ratio considerando facit_). But no such reference is made by Vico, fond as he was of expressing the debt of his own thought to the ancient philosophers; and admitting that the doctrine had some force before his time, the divergence between this earlier view and that of Vico on the knowableness of the world of man is as great as that between the assertion of the omniscience of God the Creator and the theory of knowledge which Vico was able to draw from it.