Enlightenment is man's leaving his self-caused immaturity. Immaturity is the incapacity to use one's intelligence without the guidance of another. Such immaturity is self-caused if it is not caused by lack of intelligence, but by lack of determination and courage to use one's intelligence without being guided by another. Sapere Aude! Have the courage to use your own intelligence! is therefore the motto of the enlightenment.
Natural science physics contains in itself synthetical judgments a priori, as principles. ... Space then is a necessary representation a priori, which serves for the foundation of all external intuitions.
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.
The greatest problem for the human species, the solution of which nature compels him to seek, is that of attaining a civil society which can administer justice universally.
Freedom is the alone unoriginated birthright of man, and belongs to him by force of his humanity; and is independence on the will and co-action of every other in so far as this consists with every other person's freedom.
The evil effect of science upon men is principally this, that by far the greatest number of those who wish to display a knowledge of it accomplish no improvement at all of the understanding, but only a perversity of it, not to mention that it serves most of them as a tool of vanity.
At some future day it will be proved, I cannot say when and where, that the human soul is, while in earth life, already in an uninterrupted communication with those living in another world.
Enlightenment is man's emergence from his self-imposed nonage. Nonage is the inability to use one's own understanding without another's guidance. This nonage is self-imposed if its cause lies not in lack of understanding but in indecision and lack of courage to use one's own mind without another's guidance. Dare to know!
In the natural state no concept of God can arise, and the false one which one makes for himself is harmful. Hence the theory of natural religion can be true only where there is no science; therefore it cannot bind all men together.