“The supreme misfortune is when theory outstrips performance”

1970s, Economics for the Citizen (1978)

Source: "Theory, experiment and economics," 1989, p. 151.

17 U.S. (4 Wheaton) 316, 406-407
McCulloch v. Maryland (1819)
Context: [T]he Government of the Union, though limited in its powers, is supreme within its sphere of action. This would seem to result necessarily from its nature. It is the Government of all; its powers are delegated by all; it represents all, and acts for all. Though any one State may be willing to control its operations, no State is willing to allow others to control them. The nation, on those subjects on which it can act, must necessarily bind its component parts. But this question is not left to mere reason; the people have, in express terms, decided it by saying, [p406] "this Constitution, and the laws of the United States, which shall be made in pursuance thereof," "shall be the supreme law of the land," and by requiring that the members of the State legislatures and the officers of the executive and judicial departments of the States shall take the oath of fidelity to it. The Government of the United States, then, though limited in its powers, is supreme, and its laws, when made in pursuance of the Constitution, form the supreme law of the land, "anything in the Constitution or laws of any State to the contrary notwithstanding."

[82-83, Anthony, Lewis, w:Anthony Lewis, Make No Law: The Sullivan Case and the First Amendment, Vintage, 1992, 0679739394, http://books.google.com/books?id=YElZ5GgC7E0C&lpg=PA1&pg=PT127#v=onepage&q&f=false]

Source: Growing Up Absurd (1956), p. 144.

"On the Method of Theoretical Physics" The Herbert Spencer Lecture, delivered at Oxford (10 June 1933); also published in Philosophy of Science, Vol. 1, No. 2 (April 1934), pp. 163-169., p. 165. [thanks to Dr. Techie @ www.wordorigins.org and JSTOR]
There is a quote attributed to Einstein that may have arisen as a paraphrase of the above quote, commonly given as “Everything should be made as simple as possible, but no simpler,” "Everything should be made as simple as possible, but not simpler", or “Make things as simple as possible, but not simpler.” See this article from the Quote Investigator http://quoteinvestigator.com/2011/05/13/einstein-simple/ for a discussion of where these later variants may have arisen.
The original quote is very similar to Occam's razor, which advocates that among all hypotheses compatible with all available observations, the simplest hypothesis is the most plausible one.
The aphorism "everything should be made as simple as possible, but no simpler" is normally taken to be a warning against too much simplicity and emphasizes that one cannot simplify things to a point where the hypothesis is no more compatible with all observations. The aphorism does not contradict or extend Occam's razor, but rather stresses that both elements of the razor, simplicity and compatibility with the observations, are essential.
The earliest known appearance of Einstein's razor is an essay by Roger Sessions in the New York Times (8 January 1950) http://select.nytimes.com/gst/abstract.html?res=F30615FE3559137A93CAA9178AD85F448585F9, where Sessions appears to be paraphrasing Einstein: “I also remember a remark of Albert Einstein, which certainly applies to music. He said, in effect, that everything should be as simple as it can be, but not simpler.”
Another early appearance, from Time magazine (14 December 1962) http://www.time.com/time/magazine/article/0,9171,872923,00.html: “We try to keep in mind a saying attributed to Einstein—that everything must be made as simple as possible, but not one bit simpler.”
1930s

August 22
Debates in the Federal Convention (1787)

Jewish Chronicle, 12 October 2007 http://thejc.com/home.aspx?AId=56026&ATypeId=1&search=true2&srchstr=patrick%20marber&srchtxt=1&srchhead=1&srchauthor=1&srchsandp=1&scsrch=0

Introduction à l'Étude de la Médecine Expérimentale (1865)