“We all believe that we are a certain kind of person, but we never know until we do something that proves otherwise, or until we die.”

Source: Colorless Tsukuru Tazaki and His Years of Pilgrimage

Source: The Girls' Guide to Hunting and Fishing

Source: How Proust Can Change Your Life

Response to questions about the investigation of Robert Oppenheimer's supposed Communist sympathies
Public Papers of the Presidents of the United States. Dwight D. Eisenhower (1954), p. 435
Cited in [Brendon, Piers, Ike: His Life & Times, 1st edition, 1986, Harper & Row, New York, ISBN 0-06-015508-6, p. 270 of 478, The Dawn of Tranquility]
1950s

Foreword (January 1960)
You Learn by Living (1960)
Context: One's philosophy is not best expressed in words; it is expressed in the choices one makes. In stopping to think through the meaning of what I have learned, there is much that I believe intensely, much I am unsure of. In the long run, we shape our lives and we shape ourselves. The process never ends until we die. And, the choices we make are ultimately our own responsibility.

On himself and Peter Doherty in an NME interview (2006-12-06)

Speech to a joint session of the United States Congress, Washington, D.C. (26 December 1941) http://www.winstonchurchill.org/learn/speeches/speeches-of-winston-churchill/1941-1945-war-leader/288-us-congress-1941.
The Second World War (1939–1945)
Context: When we consider the resources of the United States and the British Empire compared to those of Japan, when we remember those of China, which has so long and valiantly withstood invasion and when also we observe the Russian menace which hangs over Japan, it becomes still more difficult to reconcile Japanese action with prudence or even with sanity. What kind of a people do they think we are? Is it possible they do not realise that we shall never cease to persevere against them until they have been taught a lesson which they and the world will never forget?
Members of the Senate and members of the House of Representatives, I turn for one moment more from the turmoil and convulsions of the present to the broader basis of the future. Here we are together facing a group of mighty foes who seek our ruin; here we are together defending all that to free men is dear. Twice in a single generation the catastrophe of world war has fallen upon us; twice in our lifetime has the long arm of fate reached across the ocean to bring the United States into the forefront of the battle. If we had kept together after the last War, if we had taken common measures for our safety, this renewal of the curse need never have fallen upon us.
Do we not owe it to ourselves, to our children, to mankind tormented, to make sure that these catastrophes shall not engulf us for the third time?