"Indeed, all idealism derives from Descartes, or from Kant, or from both together, and whatever other distinguishing features a system may have, it is idealist to the extent that, either in itself, or as far as we are concerned, it makes knowing the condition of being."

“The scientific sterility of the Middle Ages has to be condemned for the same reasons which make it necessary today to condemn the philosophic sterility of scientism.”

“With Descartes the Cogito ergo sum turns into Cogito ergo res sunt .”

“As used today, the word realism means in the first place the opposite to idealism when it claims that it is possible to pass from the subject to the object.”

“Having left us with thought , and extension , does not know how to account for the union of soul and body.”

“Up to Descartes' time, and particularly during the Middle Ages, it had always been agreed that philosophy consisted in a transposition of reality into conceptual terms”

“Hume's skepticism, therefore, descends in a direct line from Cartesian mathematicism.”