“And it’s important to understand the sequence of events, and the ideas that accompanied that sequence of events that led up to the Civil War. The subtitle of my new book is Abraham Lincoln and the Coming of the Civil War, and I believe I’ve discussed the question of the nature of secession and the role of secession in that crisis, I believe, more thoroughly than I think it’s ever been discussed before.”

Interviewed in the documentary series The Civil War, 1990
Context: Any understanding of this nation has to be based, and I mean really based, on an understanding of the Civil War. I believe that firmly. It defined us. The Revolution did what it did. Our involvement in European wars, beginning with the First World War, did what it did. But the Civil War defined us as what we are and it opened us to being what we became, good and bad things. And it is very necessary, if you are going to understand the American character in the twentieth century, to learn about this enormous catastrophe of the mid-nineteenth century. It was the crossroads of our being, and it was a hell of a crossroads.

A History of the Crusades (Cambridge: Cambridge University Press, [1951-54] 1957) vol. 3 p. xiii.Steven Runciman delivered a lecture in the University of the Punjab Lahore (Pakistan) on Monday, Feb 24, 1964 at 11.00 A. M in the University of Senate Hall. The topic was " Personal Contacts between Muslims and Christians in the Middle Ages". Professor Hamid Ahmad Khan VC presided the lecture. Allama Muhammad Yousuf Gabriel attended this lecture and gave a letter to Sir S.Runciman to deliever it to Sir Bertrand Russel. Sir Steven delievered t his letter to Bertrand Russel and he sent a reply to Allama Muhammad Yousuf Gabriel but address was not Pakistan but India. The letter was returned from India to Pakistan and was handed over to Yousuf Gabriel. Sir Bertrand Russel wrote : " Since Adam and Eve ate the apple man has never abstained any folly what ever he could do and the end is atomic hell".

Letter in Harijan (1938) http://web.archive.org/20021008131454/die_meistersinger.tripod.com/gandhi9.html
1930s

Though Rickover quoted this, he did not claim to be the author of the statement. Using it in "The World of the Uneducated" in The Saturday Evening Post (28 November 1959), he prefaces it with "As the unknown sage puts it..." — It has sometimes been attributed to Eleanor Roosevelt, but without definite citation.
Some evidence for Henry Buckle (1821-1862) as the source: see p.33 quotation https://books.google.com/books?id=2moaAAAAYAAJ&q=buckle#v=snippet&q=buckle&f=false
Misattributed

Some evidence for Henry Buckle (1821-1862) as the source: see p.33 quotation https://books.google.com/books?id=2moaAAAAYAAJ&q=buckle#v=snippet&q=buckle&f=false
There are many published incidents of this as an anonymous proverb since at least 1948, and as a statement of Eleanor Roosevelt since at least 1992, but without any citation of an original source. It is also often attributed to Admiral Hyman G. Rickover but, though Rickover quoted this, he did not claim to be the author of it; in "The World of the Uneducated" in The Saturday Evening Post (28 November 1959), he prefaces it with "As the unknown sage puts it..."
Great minds discuss ideas, average minds discuss events, and little minds discuss people.
In this form it was quoted as an anonymous epigram in A Guide to Effective Public Speaking (1953) by Lawrence Henry Mouat
New York times Saturday review of books and art, 1931: ...Wanted, the correct quotation and origin of this expression: Great minds discuss ideas, average minds discuss events, small minds discuss people...
Several other variants or derivatives of the expression exist, but none provide a definite author:
Great minds discuss ideas, mediocre minds discuss events, small minds discuss personalities.
Great minds discuss ideas
Average minds discuss events
Small minds discuss people
Small minds discuss things
Average minds discuss people
Great minds discuss ideas
...Be less curious about people and more curious about ideas. (Marie Curie, undated (died 1934), as quoted in Living Adventures in Science by Henry and Dana Lee Thomas, 1972)
...Some professor of psychology who has been eavesdropping for years makes the statement that "The best minds discuss ideas; the second in ranking talk about things; while the third group, or the least in mentality, gossip about people"… (Hardware age, Volume 123, 1929)
...He now reports that, "the best minds discuss ideas; the second ranking talks about things; while the third and lowest mentality – starved for ideas – gossips about people." (Printers' Ink, Volume 139, Issue 2, 1927, p. 87)
...It has been said long ago that there were three classes of people in the world, and while they are subject to variation, for elemental consideration they are useful. The first is that large class of people who talk about people; the next class are those who talk about things; and the third class are those who discuss ideas... (H. J. Derbyshire, "Origin of mental species", 1919)
...Mrs. Conklin points out certain bad conversational habits and suggests good ones, quoting Buckle's classic classification of talkers into three orders of intelligence — those who talk about nothing but persons, those who talk about things and those who discuss ideas... (review of Mary Greer Conklin's book Conversation: What to say and how to say it in The Continent, Jan. 23, 1913, p. 118)
...[ Henry Thomas Buckle's ] thoughts and conversations were always on a high level, and I recollect a saying of his which not only greatly impressed me at the time, but which I have ever since cherished as a test of the mental calibre of friends and acquaintances. Buckle said, in his dogmatic way: "Men and women range themselves into three classes or orders of intelligence; you can tell the lowest class by their habit of always talking about persons, the next by the fact that their habit is always to converse about things; the highest by their preference for the discussion of ideas"… (Charles Stewart, "Haud immemor. Reminescences of legal and social life in Edinburgh and London. 1850-1900", 1901, p. 33 http://www.mocavo.com/Haud-Immemor-by-Charles-Stewart-Reminiscences-of-Life-in-Edinburgh-and-London-1850-1900/608008/13?browse=true#63).
Disputed

Source: Mechanical Intelligence: Collected Works of A.M. Turing

"This Charming Man," interview, Out.com (August 2008)

Source: War and peace (2005), p. 1