ascertain, but the laws of what ought to happen, even although it never does, i.e., objective practical laws, there it is not necessary to inquire into the reasons why anything pleases or displeases, how the pleasure of mere sensation differs from taste, and whether the latter is distinct from a general satisfaction of reason; on what the feeling of pleasure or pain rests, and how from it desires and inclinations arise, and from these again maxims by the co-operation of reason: for all this belongs to an empirical psychology, which would constitute the second part of physics, if we regard physics as the philosophy of nature, so far as it is based on empirical laws.

But here we are concerned with objective practical laws and, consequently, with the relation of the will to itself so far as it is determined by reason alone,