Robert Anton Wilson's 1977 Fortean Times article records Burroughs' story: Captain Clark of the Tangier ferry boasted of 23 years without accident and drowned that day; that evening the radio reported an airliner crash, pilot also named Clark, Flight 23. Wilson began collecting 23s, folded the number into the Illuminatus! trilogy, and the Discordian Law of Fives, 2 plus 3, gave it a theology. The number now has films, albums, and a Wikipedia-length rap sheet.
The story as the tradition tells it: Burroughs did not discover 23, he provoked it. A man who believed words were viruses noticed a number and the number noticed back. Discordians made it scripture with a wink, the Law of Fives, all things happen in fives, or are divisible by five, and 2 plus 3 is 5, a dogma engineered to be unfalsifiable and therefore funny.
The claim: the 23 Enigma is the cleanest demonstration that reality responds to being watched. Once you look for 23 you find it, apophenia, say the skeptics, frequency illusion, and the enigma replies: of course, that is how all omens work. The deeper claim is that Burroughs performed a working, a magic experiment, and the experiment's result is a number that now has a life of its own in millions of heads.
Burroughs started counting 23s and found them everywhere. Was he noticing the world, or building it?