Sapere Aude!

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.

-- Immanuel Kant (1724-1804), German philosopher, What is Enlightenment? (1784)