And science does not rest for us on sure foundations unless the invariability of the laws of nature is admitted.
If we do not accept this hypothesis, if we consider it possible that the uniformities of the natural world may be changed from time to time, we have no guarantee that science can progress indefinitely.

The philosophy of Descartes established this principle, which is the palladium of science; and thus the third preliminary condition was fulfilled.
2.
During the Renaissance period the authority of the Greeks and Romans had been supreme in the realm of thought, and in the interest of further free development it was necessary that this authority should be weakened.

Bacon and others had begun the movement to break down this tyranny, but the influence of Descartes was weightier and more decisive, and his attitude was more uncompromising.

He had none of Bacon's reverence for classical literature; he was proud of having forgotten the Greek which he had learned as a boy.

The inspiration of his work was the idea of breaking sharply and completely with the past, and constructing a system which borrows nothing from the dead.