For instance, the physical concepts of matter and rays correspond, according to him, to the metaphysical concepts of the thing and of movement; but whereas classical philosophy considered both as distinct, and the thing as ontologically real, modern science can not distinguish matter from rays: it is thus impossible to examine an immobile thing, which was precisely the condition for knowledge according to classical theory of knowledge (Becoming being impossible to be known, in accordance with Aristotle and Plato's theories of knowledge).