sufficient certainty, by a single appeal to the judgement of common sense, for this reason, that anything empirical which might slip into our maxims as a determining principle of the will can be detected at once by the feeling of pleasure or pain which necessarily attaches to it as exciting desire; whereas pure practical reason positively refuses to admit this feeling into its principle as a condition. The heterogeneity of the determining principles (the empirical and rational) is clearly detected by this resistance of a practically legislating reason against every admixture of inclination, and by a peculiar kind of sentiment, which, however, does not precede the legislation of the practical reason, but, on the contrary, is produced by this as a constraint, namely, by the feeling of a respect such as no man has for inclinations of whatever kind but for the law only; and it is detected in so marked and prominent a manner that even the most uninstructed cannot fail to see at once in an example presented to him, that empirical principles of volition may indeed urge him to follow their attractions, but that he can never be expected to obey anything but the pure practical law of reason alone. The distinction between the doctrine of happiness and the doctrine of morality, in the former of which empirical principles constitute the entire foundation, while in the second they do not form the smallest part of it, is the first and most important office of the Analytic of pure practical reason; and it must proceed in it with as much exactness and, so to speak, scrupulousness, as any geometer in his work. The philosopher, however, has greater difficulties to contend with here (as always in rational cognition by means of concepts merely without construction), because he cannot take any intuition as a foundation (for a pure noumenon). He has, however, this advantage that, like the chemist, he can at any time make an experiment with every man's practical reason for the purpose of distinguishing the moral (pure) principle of determination from the empirical; namely, by adding the moral law (as a determining principle) to the empirically affected will (e.g., that of the man who would be ready to lie because he can gain something thereby). It is as if the analyst added alkali to a solution of lime in hydrochloric acid, the acid at once forsakes the lime, combines with the alkali, and the lime is precipitated. Just in the same way, if to a man who is otherwise honest (or who for this occasion places himself only in thought in the position of an honest man), we present the moral law by which he recognises the worthlessness of the liar, his practical reason (in forming a judgement of what ought to be done) at once forsakes the advantage, combines with that which maintains in him respect for his own person (truthfulness), and the advantage after it has been separated and washed from every particle of reason