Unitarian Universalist Origins: Our Historic Faith--

"In sixteenth-century Transylvania, Unitarian congregations were established for the first time in history."

Gravity's Rainbow--

"For every kind of vampire, there is a kind of cross."

Unitarian minister Richard Trudeau--

"... I called the belief that

(1) Diamonds-- informative, certain truths about the world-- exist

the 'Diamond Theory' of truth. I said that for 2200 years the strongest evidence for the Diamond Theory was the widespread perception that

(2) The theorems of Euclidean geometry are diamonds....

As the news about non-Euclidean geometry spread-- first among mathematicians, then among scientists and philosophers-- the Diamond Theory began a long decline that continues today.

Factors outside mathematics have contributed to this decline. Euclidean geometry had never been the Diamond Theory's only ally. In the eighteenth century other fields had seemed to possess diamonds, too; when many of these turned out to be man-made, the Diamond Theory was undercut. And unlike earlier periods in history, when intellectual shocks came only occasionally, received truths have, since the eighteenth century, been found wanting at a dizzying rate, creating an impression that perhaps no knowledge is stable.

Other factors notwithstanding, non-Euclidean geometry remains, I think, for those who have heard of it, the single most powerful argument against the Diamond Theory*-- first, because it overthrows what had always been the strongest argument in favor of the Diamond Theory, the objective truth of Euclidean geometry; and second, because it does so not by showing Euclidean geometry to be false, but by showing it to be merely uncertain." --The Non-Euclidean Revolution, p. 255

H. S. M. Coxeter, 1987, introduction to Trudeau's book--

"There is a pleasantly discursive treatment of Pontius Pilate's unanswered question 'What is truth?'."

As noted here on Oct. 8, 2008 (A Yom Kippur Meditation), Coxeter was aware in 1987 of a more technical use of the phrase "diamond theory" that is closely related to...

* As recent Log24 entries have pointed out, diamond theory (in the original 1976 sense) is a type of non-Euclidean geometry, since finite geometry is not Euclidean geometry-- and is, therefore, non-Euclidean, in the strictest sense (though not according to popular usage).

Related material:
"A Four-Color Theorem."