From the book, "The Einstein Factor" by Win Wenger, Ph.D. and Richard Poe:
In 1788, Friedrich Schiller wrote a letter to a friend who was having difficulty coming up with fresh ideas. He wrote:
"The reason for your complaint lies in the constraint which your
intellect imposes upon your imagination, for you reject too soon and
discriminate too severely."
Schiller continued, "If the
intellect examines too closely the ideas pouring in at the gates...it
hinders the creative work of the mind."