“And we forget because we must and not because we will.”

1940s, 1940, Laureate Cross acceptance speech (July 1940)

17 U.S. (4 Wheaton) 316, 407
McCulloch v. Maryland (1819)

The Art of Doing Science and Engineering: Learning to Learn (1991)

Speech to the Imperial Conference of 1921, quoted in Correlli Barnett, The Collapse of British Power (Eyre Methuen, 1972), p. 177

Source: Let It Snow: Three Holiday Romances

Van Paassen interview (1936)
Context: We have always lived in slums and holes in the wall. We will know how to accommodate ourselves for a while. For you must not forget that we can also build. It is we who built these palaces and cities, here in Spain and America and everywhere. We, the workers. We can build others to take their place. And better ones. We are not in the least afraid of ruins. We are going to inherit the earth; there is not the slightest doubt about that. The bourgeoisie might blast and ruin its own world before it leaves the stage of history. We carry a new world here, in our hearts. That world is growing in this minute.

Address to the Democratic National Convention (15 July 1948) http://www.pbs.org/wgbh/amex/presidents/33_truman/psources/ps_convention48.html; this has often been paraphrased as: "They are wrong and we are right and I'm going to prove it to you!"

Variant: We stand separate from the world because of our gifts. Never forget that, because you may be sure the world never will.
Source: Marked