“8) History never repeats itself.”

" Some Historians http://books.google.com/books?id=E0luAAAAMAAJ&q=%22History+repeats+itself+historians+repeat+each+other%22&pg=PA20#v=onepage," Supers & Supermen: Studies in Politics, History and Letters (1920)

As quoted in Peter's Quotations: Ideas For Our Time (1977) edited by Laurence J. Peter, p. 248

Origins unclear. Earliest known match in print comes from 1970, in a collection called “Neo Poems” by Canadian artist John Robert Colombo, who recalled reading it sometime in the 1960s. Twain did say "History never repeats itself, but the Kaleidoscopic combinations of the pictured present often seem to be constructed out of the broken fragments of antique legends." in the 1874 edition of “The Gilded Age: A Tale of To-Day”. A thematic precursor, "History May Not Repeat, But It Looks Alike", appears in a 1941 article by Chicago Tribune in Illinois. (Source: Quote Investigator https://quoteinvestigator.com/2014/01/12/history-rhymes/)
Misattributed

Wars I Have Seen (1945)

Source: Reminiscences of a Stock Operator (1923), Chapter XVIII, p. 217

As quoted in Pioneers of Modern China : Understanding the Inscrutable Chinese (2005) by Khoon Choy Lee
Context: Nobody would say the cowshed was heaven and nobody would say the inhuman torture of so many victims be called a revolution of the proletariat. … A museum should be established to remind China of the follies and disasters that had fallen from 1966 to 1976. We cannot forget what had happened and history should not repeat itself.

Source: The Mirror of the Sea (1906), Ch. 8

Source: Go Set a Watchman