The will, regarded as the faculty of desire, is (in this view) one of the many natural causes in the world, viz. that cause which acts in accordance with concepts. All that is represented as possible (or necessary) by means of a will is called practically possible (or necessary); as distinguished from the physical possibility or necessity of an effect, whose cause is not determined to causality by concepts (but in lifeless matter by mechanism and in animals by instinct). Here, in respect of the practical, it is left undetermined whether the concept which gives the rule to the causality of the will, is a natural concept or a concept of freedom. But the last distinction is essential. For if the concept which determines the causality is a natural concept, then the principles are _technically practical_; whereas, if it is a concept of freedom they are _morally practical_. And as the division of a rational science depends on the distinction between objects whose cognition needs distinct principles, the former will belong to theoretical Philosophy (doctrine of Nature), but the latter alone will constitute the second part, viz. practical Philosophy (doctrine of Morals). All technically practical rules (_i.e._ the rules of art and skill generally, or of prudence regarded as skill in exercising an influence over men and their wills), so far as their principles rest on concepts, must be reckoned only as corollaries to theoretical Philosophy. For they concern only the possibility of things according to natural concepts, to which belong not only the means which are to be met with in nature, but also the will itself (as a faculty of desire and consequently a natural faculty), so far as it can be determined conformably to these rules by natural motives. However, practical rules of this kind are not called laws (like physical laws), but only precepts; because the will does not stand merely under the natural concept, but also under the concept of freedom, in relation to which its principles are called laws. These with their consequences alone constitute the second or practical part of Philosophy.