From such crooked timber as humanity is made of, no straight thing was ever constructed. - Immanuel Kant

Here as elsewhere human reason in its pure use, so long as it was not critically examined, has first tried all possible wrong ways before it succeeded in finding the one true way.

Inexperienced in the course of world affairs and incapable of being prepared for all the chances that happen in it, I ask myself only 'Can you also will that your maxim should become a universal law?' Where you cannot it is to be rejected...

I do not, therefore, need any penetrating acuteness to see what I have to do in order that my volition be morally good. Inexperienced in the course of the world, incapable of being prepared for whatever might come to pass in it, I ask myself only: can you also will that your maxim become a universal law?