Notwithstanding this force and ease of application, a categorical Imperative has not yet been proved _à priori_ actually existent; and it was allowed that it could not be proved empirically, elements of inclination, interest, &c., being inconsistent with morality. The real question is this: Is it a necessary law that all rational beings should act on maxims that they can wish, to become universal laws? If so, this must be bound up with the very notion of the will of a rational being; the relation of the will to itself being to be determined _à priori_ by pure Reason. The Will is considered as a power of self-determination to act according to certain laws as represented to the mind, existing only in rational beings. And, if the objective ground of self-determination, or _End_, is supplied by mere Reason, it must be the same for all rational beings. _Ends_ may be divided into _Subjective_, resting upon individual _Impulses_ or subjective grounds of desire; and _Objective_, depending on _Motives_ or objective grounds of Volition valid for all rational beings. The principles of action are, in the one case, _Material_, and, in the other, _Formal, i.e._, abstracted from all subjective ends. Material ends, as relative, beget only hypothetical Imperatives. But, supposed some thing, the presence of which in itself has an absolute value, and which, as End-in-self, can be a ground of fixed laws; there, and there only, can be the ground of a possible categorical Imperative, or Law of Practice. Now, such an End-in-self (not a thing with merely conditional value,--a means to be used arbitrarily) is Man and every rational being, as _Person_. There is no other objective end with absolute value that can supply to the Reason the supreme practical principle requisite for turning subjective principles of action into objective principles of volition. Rational Nature as End-in-self is a subjective principle to a man having this conception of his own being, but becomes objective when every rational being has the same from the same ground in Reason. Hence a new form (the second) to the practical Imperative: _Act so as to use Humanity (Human Nature) as well in your own person, as in the person of another, ever as end also, and never merely as means_.