“The fact that a great many scientists signed Faustian pacts with the war devil throughout the twentieth century has given science a bad name, and has discouraged many able youngsters from pursuing a scientific career.”

The Human: Science's Irrational Origins (p. 22)
Straw Dogs: Thoughts on Humans and Other Animals (2002)

The Romance of Commerce (1918), Concerning Commerce

Speech at the Albert Hall, London (3 December 1936) at a cross-party meeting organised by the League of Nations Union "in defence of freedom and peace", quoted in The Times (4 December 1936), p. 18
The 1930s

Source: Man, the State, and War (1959), Chapter I, Introduction, p. 1

An Appeal to the Young (1880)
Context: More than a century has passed since science laid down sound propositions as to the origins of the universe, but how many have mastered them or possess the really scientific spirit of criticism? A few thousands at the outside, who are lost in the midst of hundreds of millions still steeped in prejudices and superstitions worthy of savages, who are consequently ever ready to serve as puppets for religious impostors.

City Edition, Vol. 22 Issue 3, p. 5.

Source: Reinventing Gravity (2008), Chapter 3, The Beginning Of Modern Cosmology, p. 54

Source: Broca's Brain (1979), Chapter 9, “Science Fiction—A Personal View” (p. 172)

Interview in The New York Times (28 November 1993).
Context: I believe that in the 20th century, humanity has learned from many, many experiences. Some positive, and many negative. What misery, what destruction! The greatest number of human beings were killed in the two world wars of this century. But human nature is such that when we face a tremendous critical situation, the human mind can wake up and find some other alternative. That is a human capacity.