“The world's biggest problem is not sexism, racism, political polarization, war, or income inequality. The key never-ending crisis is that most people can’t or won’t think. Poor thinking skills cut cross all the usual lines to drag down societies like nothing else. Thinking well could alleviate or solve virtually all our problems.”

Source: Rules for Radicals: A Pragmatic Primer for Realistic Radicals

Introduction (p. viii)
The Eternal Champion (1970)

From 1980s onwards, Grunch of Giants (1983)

Talks at Google (Oct 28, 2014)
Context: This mind wandering mode turns out to be very different from the task engagement mode, because it's where thoughts that are loosely connected seamlessly flow into one another like in a dream.... And you begin to see connections between things that you didn't see as connected before.... non-linear kinds of thinking... This is the mode of thinking where your most creative acts are likely to occur and where problem solving is apt to occur.

Arborophilia (2005)

1930s- 1950s, The New Society (1950)

as quoted by D. D. Ryutov in [G.I. Budker: reflections & remembrances, by Boris N. Breizman, Springer, 1993, http://books.google.com/books?id=e0bxFrmNtykC&printsec=frontcover#PRA1-PA278,M1, 1-56396-070-2, 278]

On Writing (2002)

Attributed to Butler in: American Dental Association (1959) The Journal of the American Dental Association. Vol 59. p. 289