Source: Mathematicians are useful (1971), p. 1:
“Appreciate the magnificent brain you possess. Protect and nurture it. Strive to be a good skeptic and critical thinker so that fewer hours of your precious life will be squandered on dead-end beliefs. Always try to think like a scientist so that you might better know truth from fiction.”
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Guy P. Harrison 21
American skeptic author 1963Related quotes

“Better try to stay wide awake, or you might end up found dead by the lake.”
"Stay Wide Awake".
2000s, Relapse (2009)

“My wish for you… is that your skeptic-eclectic brain be flooded with the light of truth.”
Source: The First Circle

http://www.wowowow.com/entertainment/liz-smith-living-legend-madonna-398128?page=0%2C0
From American Gothic: An Interview with Elliott Carter http://edwebproject.org/carter.html (1993) by Andy Carvin.
Reported in Lucian McCarty, "Sen. Roy McDonald Comes to his decision on the same-sex marriage measure after careful consideration, remains firm in his support despite criticism", The Saratogian (June 2011).
This was on Senator McDonald's change of vote from a "no" in 2009 to a "yes" in 2011.

Source: Vehicles: Experiments in Synthetic Psychology (1984), p. 1