The whole interest of my reason, whether speculative or practical, is concentrated in the three following questions: What can I know? What should I do? What may I hope? (Critique of Pure Reason

Without man and his potential for moral progress, the whole of reality would be a mere wilderness, a thing in vain, and have no final purpose.

I should never act in such a way that I could not also will that my maxim should be a universal law.

We must not, however, begin with theology. The religion which is founded merely on theology can never contain anything of morality. Hence we derive no other feelings from it but fear on the one hand, and hope of reward on the other, and this produces merely a superstitious cult. Morality, then, must come first and theology follow; and that is religion.

An action done from duty has its moral worth, not in the purpose to be attained by it, but in the maxim according with which it is decided upon; it depends therefore, not on the realization of the object of action, but solely on the principle of volition in accordance with which, irrespective of all objects of the faculty of desire, the action has been performed.

...in its practical purpose the footpath of freedom is the only one on which it is possible to make use of reason in our conduct. Hence it is as impossible for the subtlest philosophy as for the commonest reasoning to argue freedom away.

Innocence is a splendid thing, only it has the misfortune not to keep very well and to be easily misled.

What is more, we cannot do morality a worse service than by seeing to derive it from examples. Every example of it presented to me must first itself be judged by moral principles in order to decide if it is fit to serve as an original example...even the Holy One of the gospel must first be compared with our ideal of moral perfection before we can recognize him to be such.

It is impossible to conceive anything at all in the world, or even out of it, which can be taken as good without qualification, except a good will.