"An Answer to the Question: 'What is Enlightenment?'" (By Immanuel Kant)

"Enlightenment is man’s emergence from his self-imposed immaturity. Immaturity is the inability to use one’s understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude!1 “Have courage to use your own understanding!” — that is the motto of enlightenment.
Laziness and cowardice are the reasons why so great a proportion of men, long after nature has released them from alien guidance (naturaliter maiorennes), nonetheless gladly remain in lifelong immaturity, and why it is so easy for others to establish themselves as their guardians. It is so easy to be immature. If I have a book to serve as my understanding, a pastor to serve as my conscience, a physician to determine my diet for me, and so on, I need not exert myself at all. I need not think, if only I can pay: others will readily undertake the irksome work for me. The guardians who have so benevolently taken over the supervision of men have carefully seen to it that the far greatest part of them (including the entire fair sex) regard taking the step to maturity as very dangerous, not to mention difficult. Having first made their domestic livestock dumb, and having carefully made sure that these docile creatures will not take a single step without the go-cart to which they are harnessed, these guardians then show them the danger that threatens them, should they attempt to walk alone. Now this danger is not actually so great, for after falling a few times they would in the end certainly learn to walk; but an example of this kind makes men timid and usually frightens them out of all further attempts."

First two paragraphes from Kant's text. The text is quoted from and the whole text can be found at: http://sap.ereau.de/kant/what_is_enlightenment/