“Geraldine: We must tell the truth!
Prentice: That's a thoroughly defeatist attitude.”

1963, American University speech
Context: Let us examine our attitude toward peace itself. Too many of us think it is impossible. Too many think it unreal. But that is a dangerous, defeatist belief. It leads to the conclusion that war is inevitable — that mankind is doomed — that we are gripped by forces we cannot control. We need not accept that view. Our problems are manmade — therefore, they can be solved by man. And man can be as big as he wants. No problem of human destiny is beyond human beings. Man's reason and spirit have often solved the seemingly unsolvable — and we believe they can do it again.

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 40. (from "How to Study the Bible").

Burnet, F.M. (1949) "Some aspects of the epidemiology of poliomyelitis". in: Proc. Royal Australasian College of Physicians. 4: 95-100.
Quote from 1949 on the development of a poliomyelitis vaccine, which was developed later that year.

Source: The American Presidency

Hawthorne and His Mosses (1850)

Falsehood in Wartime (1928), Introduction
Context: Lying, as we all know, does not take place only in war-time. Man, it has been said, is not "a veridical animal," but his habit of lying is not nearly so extraordinary as his amazing readiness to believe. It is, indeed, because of human credulity that lies flourish. But in war-time the authoritative organization of lying is not sufficiently recognized. The deception of whole peoples is not a matter which can be lightly regarded.
A useful purpose can therefore be served in the interval of so-called peace by a warning which people can examine with dispassionate calm, that the authorities in each country do, and indeed must, resort to this practice in order, first, to justify themselves by depicting the enemy as an undiluted criminal; and secondly, to inflame popular passion sufficiently to secure recruits for the continuance of the struggle. They cannot afford to tell the truth. In some cases it must be admitted that at the moment they do not know what the truth is.

Source: His Dark Materials, The Amber Spyglass (2000), Ch. 32 : Morning
Context: One of the ghosts — an old woman — beckoned, urging her to come close.
Then she spoke, and Mary heard her say:
"Tell them stories. They need the truth. You must tell them true stories, and everything will be well, just tell them stories."
That was all, and then she was gone. It was one of those moments when we suddenly recall a dream that we’ve unaccountably forgotten, and back in a flood comes all the emotion we felt in our sleep. It was the dream she’d tried to describe to Atal, the night picture; but as Mary tried to find it again, it dissolved and drifted apart, just as these presences did in the open air. The dream was gone.
All that was left was the sweetness of that feeling, and the injunction to tell them stories.

Source: Harriet the Spy

(said by Princess Catskin).
English Fairy Tales (1890), Preface to English Fairy Tales, Catskin