Does "keep one's cool" come from Beat slang?

Solution 1:

It's from earlier than 1966.

The best example of an earlier use seems to be the article Never Lose Your Cool New World Writing, Vol. 17 (1960) by Paul Friedman. A collection of Paul Friedman writings And If Defeated Allege Fraud: Stories By Paul Friedman also has this story and has the date "1953" after the title on page 101.

Also, The Messenger (1963) by Charles Wright:

"Well, baby," Maxine slanged, "don't blow your cool."

Also, a US music copyright catalog lists:

DON'T LOSE YOUR COOL; w & m Ronald Scalars & Celia Marshall. (c) Travis Music Co. & Ritterhouse Music, Inc.; 17Jan63 EU753541

There are much earlier examples with the similar meaning but where "cool" is modifying something, such as:

In the book The Ship and the Shore (1941) at page 133:

'Never lose your cool head in a tight situation/ Katharine Myrtle, page 243," he said, as he stepped on the rocking, swinging and bouncing planks.

Munsey's Magazine (1925)

Hungerstone, boundlessly astonished, kept his cool head, and went to her as nonchalantly as if Mrs. Hayden had never called him anything but " George."

and Sparks Goes to War Collier's 26 October 1918:

...my feeling of importance was lost as soon as I lost my cool reserve and began asking questions...

Solution 2:

I'm going to post this as an answer because it's too long for a comment, but it's really just an extended comment.

The earliest instance I found in newspapers (from newpaperarchive.com) is from August 24, 1957, in the Alpine Sul Ross Skyline paper in Alpine, TX, in a story about someone in the Civil War. "Regardless how he met his end, he was a leader who kept his cool."

Also from newspapers (as background), from about 1921 on, in articles about sports, "he kept his cool head."

1927: "kept his teammates cool and at ease"

1928: "kept his cool-headed style"

1930: "kept his K___ team cool and collected"

1930: "kept cool and used his head"

1931: "kept his cool nerve"

1936: "kept his smile cool"

1937: "kept his brain cool"

1939: "kept his head cool" (also 1945)

1949: "kept his cool nerve, his patience, and his head"

1951: "cool style of play"

1952: "kept his Preston mates cool as cucumbers while the clock ran out"

1955: "kept his head cool"

1965: "kept his campaign cool and calm"

San Rafael Daily Independent Journal, September 23, 1965, "kept his cool"

1966 and later: "kept his cool"

Many of the above cases are multiple examples--i.e., there's a wire story that ran in several or perhaps many newspapers.

I'd conclude that "cool" as a noun is a shortening of adjective form--cool head, cool nerve.

Addition:

June 1, 1958, New York Times Book Review, http://www.nytimes.com/1958/06/01/archives/pens-filled-with-protest-the-beat-generation-and-the-angry-young.html. This is a book review entitled "Pens Filled with Protest" of The Beat Generation and the Angry Young Men, ed. Feldman & Gartenberg (an anthology) and includes the following paragraph labelling "cool" an original word and connecting with the Beat Generation--Kerouac et.al.

Even American despair is optimistic; in Europe despair is cynical or tragic. Beat, cool, hip, swing, square are emotive and original words, and although the desire of the Beat to sharpen his own senses so that he can concentrate and improve his dialogue with existence--not social existence, however--often leads, in this volume, to outpourings of self-pity and hysteria, it also leads to something less trite in American writing.