“We are a sum total of what we have learned from all who have taught us, both great and small.”

Source: The Lady of the Rivers

Address to Polaroid employees at Symphony Hall in Boston, Massachusetts (5 February 1960), as quoted in Insisting on the Impossible : The Life of Edwin Land (1998) by Victor K. McElheny, p. 198
Context: The world is a scene changing so rapidly that it takes every bit of intuitive ability you have, every brain cell each one of you has, to make the sensible decision about what to do next. You cannot rely upon what you have been taught. All you have learned from history is old ways of making mistakes. There is nothing that history can tell you about what we must do tomorrow. Only what we must not do.

Source: She Is the Darkness (1997), Chapter 95 (p. 614)

1940s, Victory broadcast (1945)
Context: We have known the bitterness of defeat and the exultation of triumph, and from both we have learned there can be no turning back. We must go forward to preserve in peace what we won in war.
A new era is upon us. Even the lesson of victory itself brings with it profound concern, both for our future security and the survival of civilization. The destructiveness of the war potential, through progressive advances in scientific discovery, has in fact now reached a point which revises the traditional concepts of war.

Vesicles make clouds; they are trifles light as air, but then they make drops, and drops make showers, rain makes torrents and rivers, and these can alter the face of a country, and even keep the ocean to its proper fulness and use. It teaches a continual comparison of the small and great, and that under differences almost approaching the infinite, for the small as often contains the great in principle, as the great does the small; and thus the mind becomes comprehensive. It teaches to deduce principles carefully, to hold them firmly, or to suspend the judgment, to discover and obey law, and by it to be bold in applying to the greatest what we know of the smallest. It teaches us first by tutors and books, to learn that which is already known to others, and then by the light and methods which belong to science to learn for ourselves and for others; so making a fruitful return to man in the future for that which we have obtained from the men of the past.
Lecture notes of 1858, quoted in The Life and Letters of Faraday (1870) by Bence Jones, Vol. 2, p. 403

Fors Clavigera,, letter xlii, ( 1 June 1874 https://archive.org/stream/forsclavigera02ruskiala#page/204/mode/2up; quoted by William Archer in America To-Day).
Fors Clavigera (1871-1878 and 1880-1884)

Source: Sons of Destiny

Day of Affirmation Address (1966)
Variant: Few will have the greatness to bend history, but each of us can work to change a small portion of the events, and then the total — all of these acts — will be written in the history of this generation.