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

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.

O ser humano é aquilo que a educação faz dele.

...When he puts a thing on a pedestal and calls it beautiful, he demands the same delight from others. He judges not merely for himself, but for all men, and then speaks of beauty as if it were the property of things.

The world of sense, if it is limited, lies necessarily within the infinite void. If we ignore this, and with it, space in general, as an a priori condition of the possibility of phenomena, the whole world of sense vanishes, which alone forms the object of our enquiry.

The public use of one’s reason must always be free, and it alone can bring about enlightenment among men.

What can I know? What ought I to do? What can I hope?

Innocence is indeed a glorious thing, only, on the other hand, it is very sad that it cannot well maintain itself, and is easily seduced.