“The Court's reasoning adds up to this: The Commission must be sustained because of its accumulated experience in solving a problem with which it had never before been confronted! I give up. Now I realize fully what Mark Twain meant when he said, 'The more you explain it, the more I don't understand it.”

Variant: I always wanted to be something, but now I see I should have been more specific.

Source: Information, The New Language of Science (2003), Chapter 15, Ultimate Speed, The information speed limit, p. 135

Source: Summer Sisters

Act i, scene 4
Queen Mary: A Drama (published 1876)

1880s, Personal Memoirs of General U. S. Grant (1885)
Context: As we approached the brow of the hill from which it was expected we could see Harris' camp, and possibly find his men ready formed to meet us, my heart kept getting higher and higher until it felt to me as though it was in my throat. I would have given anything then to have been back in Illinois, but I had not the moral courage to halt and consider what to do; I kept right on. When we reached a point from which the valley below was in full view I halted. The place where Harris had been encamped a few days before was still there and the marks of a recent encampment were plainly visible, but the troops were gone. My heart resumed its place. It occurred to me at once that Harris had been as much afraid of me as I had been of him. This was a view of the question I had never taken before; but it was one I never forgot afterwards. From that event to the close of the war, I never experienced trepidation upon confronting an enemy, though I always felt more or less anxiety. I never forgot that he had as much reason to fear my forces as I had his. The lesson was valuable.

Account of his effort as Colonel of the 21st Infantry of Illinois, to engage Confederate Colonel Thomas Harris in northern Missouri, Ch. 18.

The Forgotten Ideas in Computer Science

Attributed to Greenspan by Rupert Cornwell, "Alan Greenspan: The buck starts here" http://www.independent.co.uk/news/people/profiles/alan-greenspan-the-buck-starts-here-595789.html, The Independent, 27 April 2003, citing an unspecified Capitol Hill hearing. However, as Ralph Keyes notes in The Quote Verifier (2006, p. 233), "This popular tongue twister gets attributed to the obfuscator du jour." The earliest known print attribution is to Robert McCloskey, U.S. State Department spokesman, by Marvin Kalb, CBS reporter, in TV Guide, 31 March 1984, citing an unspecified press briefing during the Vietnam war.
Earlier attributions include: "a high government official", Annual Report, North American Gas Tax Conference, Federation of Tax Administrators, 1967; Jerry Lewis (a sign pasted on the camera during a movie shoot), by Dick Kleiner, Hollywood Correspondent, Sumter Daily Item, Feb. 4, 1970; a sign on the desk of Suzanne Schroeder, collector of bureaucratic gobbledygook, AP wire story, Sarasota Herald-Tribune, July 3, 1973; Jack Nicklaus paraphrasing Richard Nixon, by Larry Dorman, The Palm Beach Post, Dec. 8, 1979; and "a Hollywood film director", by J.D. Douglas, The Third Way, 29 December 1977. Additionally, a thesis monograph by Michael David Katz, Georgia State University, 1973 is titled with the quote.
On the back of the first Stealers Wheel album, a very similar statement attributed to band member Rod Coombes is found: "We know that you believe you understand what you think we said, but we are not sure you realize that what you heard is not what we meant." The album was released in 1972.
See Richard Nixon: "Now, when individuals read the entire transcript of the [March] 21st [1973] meeting, or hear the entire tape, where we discussed all these options, they may reach different interpretations, but I know what I meant, and I know also what I did"
Misattributed