Does anybody know the origin of the phrase 'cook the books'? I
couldn't find an etymology newsgroup so I posted this here.

It has a nice rhyming ring to it, but "cook" meaning "fraudulently adjust"
is used elsewhere too. The only reference in my own experience is in John
Buchan's "Greenmantle" (sequel to "The 39 Steps") where our hero doesn't
want to continue his journey into Turkey with "cooked documents".

Probably means "altered state" by analogy and by contrast with "raw" meaning
"original".

OED has:

---------------
cook, v.
3. c. To present in a surreptitiously altered form, for some purpose; to
manipulate, doctor, falsify, tamper with. colloq.

  1636 EARL OF STRAFFORD Lett. (1739) II. 16 The Proof was once clear,
however they have cook'd it since. 1751 SMOLLETT Per. Pic. xcviii, Some
falsified printed accounts, artfully cooked up, on purpose to mislead
and deceive. 1848 MILL Pol. Econ. I. ix. 2 These accounts, even if
cooked, still exercise some check. 1872 J. A. H. MURRAY Introd. Compl.
Scot. 117 The editor was attacked by..Pinkerton, for not printing the
text as a classic, i.e. cooking the spelling, etc., as he himself
would have done. 1875 STUBBS Const. Hist. III. xx. 410 Occasionally the
sealers may have quietly cooked the return.
---------------

Very likely; but, oddly, I have heard it used by scientists, with
respect to data, and they use "raw" in a way that is not at all the
opposite.  Cooked data are data that have been altered to suit the
theory; raw data are data that have not been processed at all, even
(e.g.) to allow for calibration of the instruments.

Last I heard, tho, "fudged" was more common than "cooked".
--

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