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

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.

Freedom is the alone unoriginated birthright of man, and belongs to him by force of his humanity.

The greatest human quest is to know what one must do in order to become a human being.

God, freedom, and immortality are untenable in the light of pure reason.

It is never too late to become reasonable and wise.

This spirit of freedom is expanding even where it must struggle against the external obstacles of governments that misunderstand their own function. Such governments are illuminated by the example that the existence of freedom need not give cause for the least concern regarding public order and harmony in the commonwealth. If only they refrain from inventing artifices to keep themselves in it, men will gradually raise themselves from barbarism.