Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from anoth… - Immanuel Kant

If there is any science man really needs it is the one I teach, of how to occupy properly that place in creation that is assigned to man, and how to learn from it what one must be in order to be a man.

If I have a book that thinks for me, a pastor who acts as my conscience, a physician who prescribes my diet, and so on... then I have no need to exert myself. I have no need to think, if only I can pay; others will take care of that disagreeable business for me.

Zwei Dinge erfüllen das Gemüt mit immer neuer und zunehmender Bewunderung und Ehrfurcht, je öfter und anhaltender sich das Nachdenken damit beschäftigt: der gestirnte Himmel über mir und das moralische Gesetz in mir.