The Metaphysics of Morals by Immanuel Kant Chapter 1 Page 32

is what constitutes duty, to which every other motive must give place, because it is the condition of a will being good in itself, and the worth of such a will is above everything.

Thus, then, without quitting the moral knowledge of common human reason, we have arrived at its principle. And although, no doubt, common men do not conceive it in such an abstract and universal form, yet they always have it really before their eyes and use it as the standard of their decision.

Here it would be easy to show how, with this compass in hand, men are well able to distinguish, in every case that occurs, what is good, what bad, conformably to duty or inconsistent with it, if, without in the least teaching them anything new, we only, like Socrates, direct their attention to the principle they