Jackie,

The reason I think the quote might be one of a mystic or some kind of religious writer is because the quote always appears in the bar sections of the story where Cearrbhach consistently visualizes the bartenders as priests. At one point in one bar scene Cearrbhach has two minah birds each chant one part of the leit motif:

Minah #1: Chicanery girds..

Minah #2: Robes! Infidels!

Everyone sitting around the anti-hero lifts the tankards on cue and guzzles them outright everytime the second minah says, "Infidels!".

The book was published in 1928, was only moderately well-received, but was published again in 1989. I think it's interesting because of the subplot that deals with quantum physics, perhaps the first novel to take a close look at a science that cannot be easily understood by gamblers.