Schopenhauer and the Faculty of Reason

In his World as Will and Representation at #8 we have:

As from the direct light of the sun to the borrowed reflected light of the moon, so do we pass from the immediate representation of perception, which stands by itself and is its own warrant, to reflection, to the abstract, discursive concepts of reason (Vernunft), which have their whole content only from that knowledge of perception, and in relation to it.