[Aristotle formal logic thus far (1787)] has not been able to advance a single step, and hence is to all appearances closed and completed.

There is no virtue in penance and fasting which waste the body; they are only fanatical and monkish.

Immaturity is the incapacity to use one's intelligence without the guidance of another.

The light dove, in free flight cutting through the air the resistance of which it feels, could get the idea that it could do even better in airless space. Likewise, Plato abandoned the world of the senses because it posed so many hindrances for the understanding, and dared to go beyond it on the wings of the ideas, in the empty space of pure understanding.

Human reason is by nature architectonic.

The existence of the Bible, as a book for the people, is the greatest benefit which the human race has ever experienced. Every attempt to belittle it is a crime against humanity.

Have the courage to use your own reason- That is the motto of enlightenment. "Foundations of the Metaphysics of Morals" (1785)