“The general notions about human understanding... which are illustrated by discoveries in atomic physics are not in the nature of things wholly unfamiliar, wholly unheard of, or new. Even in our own culture they have a history, and in Buddhist and Hindu thought a more considerable and central place. What we shall find is an exemplification, an encouragement, and a refinement of old wisdom.”

Radcliffe Commencement Address (16 June 1954), published as "The Illusion of Total Security" in The Atlantic Monthly, # 194 (August 1954)
Context: A foreign policy aimed at the achievement of total security is the one thing I can think of that is entirely capable of bringing this country to a point where it will have no security at all. And a ruthless, reckless insistence on attempting to stamp out everything that could conceivably constitute a reflection of improper foreign influence in our national life, regardless of the actual damage it is doing to the cost of eliminating it, in terms of other American values, is the one thing I can think of that should reduce us all to a point where the very independence we are seeking to defend would be meaningless, for we would be doing things to ourselves as vicious and tyrannical as any that might be brought to us from outside.
This sort of extremism seems to me to hold particular danger for a democracy, because it creates a curious area between what is held to be possible and what is really possible — an area within which government can always be plausibly shown to have been most dangerously delinquent in the performance of its tasks. And this area, where government is always deficient, provides the ideal field of opportunity for every sort of demagoguery and mischief-making. It constitutes a terrible breach in the dike of our national morale, through which forces of doubt and suspicion never cease to find entry. The heart of our problem, here, lies in our assessment of the relative importance of the various dangers among which we move; and until many of our people can be brought to understand that what we have to do is not to secure a total absence of danger but to balance peril against peril and to find the tolerable degree of each, we shall not wholly emerge from these confusions.

Strange Horizons interview (2004)
Context: Faeries might have been wandering around in Victorian England. I can believe that. But it is a more difficult thing to think that they might be wandering around Camden Town now.
It is more of a jump, but I find that more interesting in many ways. The irruption of the supernatural into our world is a much more enticing notion to explore than the same thing happening in some past time, or in a wholly imaginary world.

“The Case for a Dynamic Economy,” Hoover Daily Report (Sept. 22, 2003)

Preface To The 2011 edition, p. xi
The Expanding Circle: Ethics, Evolution, and Moral Progress (1981)

as quoted in Poems http://books.google.com.mx/books?id=Ep4tAAAAMAAJ&printsec=frontcover&vq=%22The+love+of+God%22#v=onepage&q=%22The%20love%20of%20God%22&f=false, from the Provensal Of Bernard Rascas

Truth and Knowledge http://wn.rsarchive.org/Books/GA003/TaK/GA003_index.html, preface

Science and the Unseen World (1929)

As quoted in Popper (1973) by Bryan Magee

Dissertation for doctor of philosophy in christian education (May 25, 1991)