“And captains that we thought were dead,
And dreamers that we thought were dumb,
And voices that we thought were fled,
Arise, and call us, and we come;
And "search in thine own soul," they cry;
"For there, too, lurks thine enemy."”

Source: Ender's Game

On the Death of Mr. William Harvey; reported in Bartlett's Familiar Quotations, 10th ed. (1919).

New York Magazine interview http://nymag.com/news/politics/22322/ (16 October 2006)
Context: Language has always been important in politics, but language is incredibly important to the present political struggle. Because if you can establish an atmosphere in which information doesn't mean anything, then there is no objective reality. The first show we did, a year ago, was our thesis statement: What you wish to be true is all that matters, regardless of the facts. Of course, at the time, we thought we were being farcical.

Source: The Sense of an Ending

http://www.gamespot.com/features/sidlegacy/interview.html

Source: Alias Grace

As rendered by T. Byrom (1993), Shambhala Publications.
There is no quote from the Pali Canon that matches up with any of these. The closest quote to this is in the Majjhima Nikaya 19:
"Whatever a monk keeps pursuing with his thinking & pondering, that becomes the inclination of his awareness. If a monk keeps pursuing thinking imbued with sensuality, abandoning thinking imbued with renunciation, his mind is bent by that thinking imbued with sensuality. If a monk keeps pursuing thinking imbued with ill will, abandoning thinking imbued with non-ill will, his mind is bent by that thinking imbued with ill will. If a monk keeps pursuing thinking imbued with harmfulness, abandoning thinking imbued with harmlessness, his mind is bent by that thinking imbued with harmfulness." Sources: http://www.accesstoinsight.org/tipitaka/mn/mn.019.than.html
Misattributed

A Heritage of Stars (1977)