To man is vouchsafed, not science, but only consciousness, which merely traverses objects without being able to show the genus or form whence they proceed. The truth of consciousness is the human side of divine wisdom, related to it as the surface to the solid: rather than truth, we ought to call it certitude. For God, _intellegere,_ understanding; for man only _cogitare,_ thought, the faculty that gleans elements of reality, but can never gather them all. For God, true demonstration; for man, observations undemonstrated and unscientific, but either certain through indubitable evidence, probable through sound reasoning, or convincing because of a plausible guess. Certitude, the truth of consciousness, is not science; but it is not on that account false. Vico was careful not to call the theories of Descartes false: his intention was only to lower them from complete truth to fragmentary truth, from science to consciousness. _Cogito ergo sum_ is very far from false. That we find it expressed by Plautus's Sosia is an argument not for rejecting it, but for accepting it; only, as a truth of simple consciousness. Thought is not the cause of my existence, and as such is not the ground of scientific knowledge of that existence. If it were, since man, as the Cartesians admitted, consists of body and mind, thought would be the cause of the body: a doctrine which would plunge us into all the mazes of the controversy on the mutual effects of mind and matter. The _cogito,_ then, is a mere sign or indication of my existence, and nothing more. The clear and distinct idea cannot serve as a criterion even of the mind itself, to say nothing of other things; since the mind, though it knows itself, does not create itself, and accordingly is ignorant of the genus or mode by which it has this knowledge. But the clear and distinct idea is all that is granted to human thought, and, as the only wealth it possesses, is beyond price. For Vico, too, metaphysic holds the highest place among the human sciences, and all others depend upon it; but while for Descartes it can proceed by a method of absolute demonstration parallel to that of geometry, for Vico it must be satisfied with probabilities. It is a science not by causes, but of causes. And with probabilities it has been content in its greatest periods, in ancient Greece and in Italy at the Renaissance. Whenever, intoxicated by the arrogance that declares that "a wise man has no opinions" (_sapientem nihil opinati_), it has sought to abandon the probable, it has set its feet upon the path of confusion and decadence. The existence of God is certain, but not scientifically demonstrable; and any attempt at such a demonstration must be considered a proof not so much of piety as of impiety, since to demonstrate God we must create him: man must become the creator of God. Similarly we must accept as true all that God has revealed; but we must not ask how it comes to be true. That we can never understand.