Lectures 21st and 22nd, compressed into one (Ed. 1846) contain the application of the foregoing principles, and the answer to the question, what our duties are. Duty being absolute, truth becomes obligatory, and absolute truth being known by the reason only, to obey the law of duty is to obey reason. But what actions are conformable to reason? The characteristic of reason he takes to be Universality, and this will appear in the motives of actions, since it is these that confer on actions their morality. Accordingly, the sign whereby to discover whether an action is duty, is, if its motive when generalized appear to the reason to be a maxim of universal legislation for all free and intelligent beings. This, the norm set up by Kant, as certainly discovers what is and is not duty, as the syllogism detects the error and truth of an argument. To obey reason is, then, the first duty, at the root of all others, and itself resting directly upon the relation between liberty and reason; in a sense, to remain reasonable is the sole duty. But it assumes special forms amid the diversity of human relations. He first considers the relations wherein we stand to ourselves and the corresponding duties. That there should be any such duties is at first sight strange, seeing we belong to ourselves; but this is not the same as having complete power over ourselves. Possessing liberty, we must not abdicate it by yielding to passions, and treat ourselves as if there were nothing in us that merits respect. We are to distinguish between what is peculiar to each of us, and what we share with humanity. Individual peculiarities are things indifferent, but the liberty and intelligence that constitute us persons, rather than individuals, demand to be respected even by ourselves. There is an obligation of self-respect imposed upon us as moral persons that was not established, and is not to be destroyed, by us. As special cases of this respect of the moral person in us, he cites (1) the duty of _self-control_ against anger or melancholy, not for their pernicious consequences, but as trenching upon the moral dignity of liberty and intelligence; (2) the duty of _prudence_, meaning providence in all things, which regulates courage, enjoins temperance, is, as the ancients said, the mother of all the virtues,--in short, the government of liberty by reason; (3) _veracity_; (4) duty towards the _body_; (5) duty of _perfecting_ (and not merely keeping intact) the intelligence, liberty, and sensibility that constitute us moral beings.