That external constraint, so far as it withstands that which hinders the external freedom that agrees with general laws (as an obstacle of the obstacle thereto), can be consistent with ends generally, is clear on the principle of contradiction, and I need not go beyond the notion of freedom in order to see it, let the end which each may be what he will. Accordingly, the supreme principle of jurisprudence is an analytical principle. On the contrary the principle of ethics goes beyond the notion of external freedom and, by general laws, connects further with it an end which it makes a duty. This principle, therefore, is synthetic. The possibility of it is contained in the deduction (SS ix).

This enlargement of the notion of duty beyond that of external freedom and of its limitation by the merely formal condition of its constant harmony; this, I say, in which, instead of constraint from without, there is set up freedom within, the power of self-constraint, and that not by the help of other inclinations, but by pure practical reason (which scorns all such help), consists in this fact, which raises it above juridical duty; that by it ends are proposed from which jurisprudence altogether abstracts. In the case of the moral imperative, and the supposition of freedom which it necessarily involves, the law, the power (to fulfil it) and the rational will that determines the maxim, constitute all the elements that form the notion of juridical duty. But in the imperative, which commands the duty of virtue, there is added, besides the notion of self-constraint, that of an end; not one that we have, but that we ought to have, w............