“History teaches us that the capacity for things to get worse is limitless.”
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Chalmers Johnson 1
American political scientist 1931–2010Related quotes
On her worldly view of poetry in “Poet Lucille Clifton: 'Everything Is Connected'” https://www.npr.org/templates/story/story.php?storyId=124113507 in NPR (2010 Feb 28)

“Things get worse before they get better.”

"A Pledge of Allegiance" - speech for "I Am an Amercan Day" Central Park, New York, New York. (20 May 1945) Hand credited H. G. Wells with inspiring some of the ideas expressed in this speech.
Extra-judicial writings
Context: We may not stop until we have done our part to fashion a world in which there shall be some share of fellowship; which shall be better than a den of thieves. Let us not disguise the difficulties; and, above all, let us not content ourselves with nobel aspirations, counsels of perfection, and self-righteous advice to others. We shall need the wisdom of the serpent; we shall have to be content with short steps; we shall be obliged to give and take; we shall face the strongest passions of mankind — our own not the least; and in the end we shall have fabricated an imperfect instrument. But we shall not wholly have failed; we shall have gone forward, if we bring to our task a pure and chastened spirit, patience, understanding, sympathy, forbearance, generosity, fortitude, and, above all, an inflexible determination. The history of man has just begun; in the aeons which lie before him lie limitless hope or limitless despair. The choice is his; the present choice is ours. It is worth the trial.

“History is is filled with brilliant people who wanted to fix things and just made them worse.”
Source: Lullaby (2002), Chapter 39

“Let me recite what history teaches. History teaches.”
If I Told Him: A Completed Portrait of Picasso (1923). First published in Vanity Fair.