1. The relation of duty to a given desire. As any desire arises, it will be, except so far as character has already been moralized, a demand for its own satisfaction; the desire, in a word, will be isolated. In so far, duty will be in a negative attitude towards the desire; it will insist first upon its limitation, and then upon its transformation. So far as it is merely limitative, it demands the denying of the desire, and so far assumes a coercive form. But this limitation is not for its own sake, but for that of the transformation of desire into a freer and more adequate form--into a form, that is, where it will carry with it, when it passes into action, _more of activity_, than the original desire would have done. Does duty itself disappear when its constraint disappears? On the contrary, so far as an act is done unwillingly, under constraint, so far the act is impure, and _undutiful_. The very fact that there is need of constraint shows that the self is divided; that there is a two-fold interest and purpose--one in the law of the activity according to function, the other in the special end of the particular desire. Let the act be done _wholly as duty_, and it is done wholly for its own sake; love, passion take the place of constraint. This suggests: 2. Duty for duty's sake. It is clear that such an expression states a real moral fact; unless a duty is done _as_ duty it is not done morally. An act may be outwardly just what morality demands, and yet if done for the sake of some private advantage it is not counted moral. As Kant expresses it, an act must be done not only in accordance with duty, but _from duty_. This truth, however, is misinterpreted when it is taken to mean that the act is to be done for the sake of duty, and duty is conceived as a third thing outside the act itself. Such a theory contradicts the true sense of the phrase 'duty for duty's sake', for it makes the act done not for its own sake, but as a mere means to an abstract law beyond itself. 'Do the right because it is the right' means do the right _thing_ because it _is_ the right thing; that is, do the act disinterestedly from interest in the act itself. A duty is always some act or line of action, not a third thing outside the act to which it is to conform. In short, duty means _the act which is to be done_, and 'duty for duty's sake' means do the required act as it really is; do not degrade it into a means for some ulterior end. This is as true in practice as in theory. A man who does his duty not for the sake of the acts themselves, but for the sake of some abstract 'ideal' which he christens duty in general, will have a morality at once hard and barren, and weak and sentimental. 3. The agency of moral authority in prescribing moral law and stimulating to moral conduct.