:	''"In theory there is no difference between theory and practice. In practice there is."''
		 :	-- YogiBerra
		 :	http://www.cyber-nation.com/victory/quotations/authors/quotes_berra_yogi.html
		 :	http://www.quotemeonit.com/berra.html

Another source, http://www.quotationspage.com/quotes/Chuck_Reid/, assigns this quote to Chuck Reid.

Zaadz.com says this is a quote of Jan van de Snepscheut, a dutch Mathematician.  http://www.zaadz.com/quotes/authors/jan_van_de_snepscheut/

''"It may come out all right in practice, but it'll '''never''' work in theory!"''

''"In theory, practice is simple."''  (Source: TrygveReenskaug)

	 :	''"Reality is the murder of a beautiful theory by a gang of ugly facts."''
		 :	-- RobertGlass?

That is based or misquoted from Aldos Huxley. The quote is:
	 :	"The great tragedy of science -- the slaying of a beautiful hypothesis by an ugly fact."
		 :	-- Thomas Huxley
The paraphrase is pretty pithy, though.
* So is it Aldos or Thomas?

Most likely it's Thomas, and it's "Aldous" Huxley ''(AldousHuxley)'', who was an author. Thomas Henry Huxley was an outspoken defender of Darwin's theory of evolution in the mid 1800's. See http://www.ucmp.berkeley.edu/history/thuxley.html for Thomas Huxley bio information.

''In theory, this quote actually originated somewhere. In practice it is impossible for us to know... -- JohnClonts''

''In theory, theory and practice are the same. In practice, they are not.''
-- AlbertEinstein

More "theory" quotes at... http://www.quotemeonit.com/theory.html [BrokenLink? All I see is an advertisement on this page.]

I rather like RobertGrossblatt's variation: ''theory and reality are only theoretically related.'' It's vastly more succinct and far more pithy.

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Clearly what we need is a theory compiler that automatically transforms to practice on its output! -- DougMerritt (a big fan of automation and compilers, but a little hazy on practicality, thus the wish)

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"The DifferenceBetweenTheoryAndPractice is in theory somewhat smaller than in practice" was my signature on the usenet for many years. I know I've heard it somewhere, but I can't tell where. Does anyone know? -- FrankWestphal

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"Beware of bugs in the above code; I have only proved it correct, not tried it." - Donald E. Knuth ''(DonKnuth)''
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Nonsense. If reality disagrees with theory, reality wins. Always. That's science.

''Maybe a DifferenceBetweenTheoryAndBelief -- an exploration of the PhilosophyOfScience''

I don't quite feel like starting those pages, but I can recommend an excellent read:

''The Meaning of It All'' By RichardFeynman

http://images.amazon.com/images/P/0738201669.01._PE_PI_SCMZZZZZZZ_.jpg
[ISBN: 0738201669] Collection of Lectures

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"Reality wins. Always. That's science."

''In theory'', that's science. But in reality, science is sometimes practiced differently. -- FalkBruegmann

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Some miscellaneous thoughts on theory and reality.

* The purpose of theory is to predict future observations.
* Theory is validated by how well it explains past observations.
* The predictive nature of theory is dependent upon how well the future observations reflect the past data selected for validation. The more the future differs from the past, the greater uncertainty surrounds the prediction.
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''I really need to graduate. I've lost the ability to discern theory from practice''