Here is what Karl himself has to say on the subject
at page 170, para two of his autobiography, Mostly On
The Edge:

"The wording itself was buried in a long letter
written to me by Harry Jaffa, known then as a
historian of the Lincoln period, now a professor at
Claremont State College in California. He later said
that he had gotten the phrase from a Lincoln speech.
The novelist Taylor Caldwell said she had traced it
to Roman antiquity. I had the opportunity to make it
famous in the acceptance speech, which I wrote for
the senator."

It seems reasonable to share credit for this phrase
with Jaffa, but it is also evident that it was Karl's
judgment and decision to use the quote in the speech
he rightly deserves credit for writing on Barry's
behalf.

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