They were quite prepared to accept what Descartes only wished to establish, and found so hard to establish, by inquiring back into the ultimate source of all knowledge: namely, the absolute metaphysical validity of the objective sciences, or, taking these together, of philosophy as the one objective universal science; or, what comes to the same thing, the right of the knowing ego to let its rational constructs, in virtue of the self evidences occurring in its mens, count as nature with a meaning transcending this ego.