Great minds discuss ideas, average minds discuss events, small minds discuss people.
Source, in full
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.
Notes from Wikiquote
Some evidence for Henry Buckle (1821-1862) as the source: see p.33 quotation