“I'm a conundrum. Or an enigma. I forget which.”

Le monde offre énormément d’énigmes dont le mot paraît difficile à trouver. Il y a des intrigues multipliées.
Part I, ch. IV.
Letters of Two Brides (1841-1842)

New Theories of Everything (2007)
Context: Scanning the past millennia of human achievement reveals just how much has been achieved during the last three hundred years since Newton set in motion the effective mathematization of Nature. We found that the world is curiously adapted to a simple mathematical description. It is enigma enough that the world is described by mathematics; but by simple mathematics, of the sort that a few years energetic study now produces familiarity with, this is an enigma within an enigma.<!--Ch. 1, p. 2

Quoted in Kubrick : Inside a Film Artist's Maze (2000) by Thomas Allen Nelson, p. 10

Source: Foucault's Pendulum

Source: A Visit from the Goon Squad

"The 23 Phenomenon" in Fortean Times 23 (1977)<!-- DEAD LINK as of 2015·03·28 published online (May 2007) http://www.forteantimes.com/features/commentary/396/the_23_phenomenon.html -->, also quoted in "The hidden roots of the 23 Enigma" by Theo Paijmans at the Charles Forte Institute (13 May 2010) http://blogs.forteana.org/node/119
Context: I first heard of the 23 Enigma from William S. Burroughs, author of Naked Lunch, Nova Express, etc. According to Burroughs, he had known a certain Captain Clark, around 1960 in Tangier, who once bragged that he had been sailing 23 years without an accident. That very day, Clark’s ship had an accident that killed him and everybody else aboard. Furthermore, while Burroughs was thinking about this crude example of the irony of the gods that evening, a bulletin on the radio announced the crash of an airliner in Florida, USA. The pilot was another Captain Clark and the flight was Flight 23.

Source: Last Breath

Source: The Angel's Game