Immanuel Kant 1784 . Konigsberg in Prussia, 30th September, 1784. Enlightenment is man's emergence from his self-incurred immaturity.
Immaturity is the inability to use one's own understanding without the guidance of another.
This immaturity is self-incurred if its cause is not lack of understanding, but lack of resolution and courage to use it without the guidance of another. For the same reasons, it is all too easy for others to set themselves up as their guardians. If I have a book to have understanding in place of me, a spiritual adviser to have a conscience for me, a doctor to judge my diet for me, and so on, I need not make any efforts at all. Having first infatuated their domesticated animals, and carefully prevented the docile creatures from daring to take a single step without the leading-strings to which they are tied, they next show them the danger which threatens them if they try to walk unaided. Now this danger is not in fact so very great, for they would certainly learn to walk eventually after a few falls.