Casting lots for divination

In Jack Vance's novel The Chasch, part of his Planet of Adventure series, the magicians of the emblem tribe practice divination by casting lots:

The Chief Magician departed, to return with a box carved from a single huge bone. He turned to Jad Piluna. "To which moon do you call for justice?" [..] The Chief Magician reached into the box, brought forth a disk, on one side pink, on the other blue. "Stand clear, all!" He spun the disk into the air. It tilted, wobbled, seemed to float and glide, and landed with the pink side on top. "Az, moon of virtue, has decided innocence!" called the magician. "Braz has seen no cause to act."

This is a good example of how Vance's imagined societies aren't as implausible as they seem at first sight. The casting of lots for divination occurs in a few places of the Hebrew Bible; in fact the Urim and Thummim may have served for that purpose.

Another reality-inspired (and not at all exotic, judging from current events) bit in Vance's work is the custom of awaile, depicted in The Wannek.

In this post of his blog, John Crowley calls for sf/fantasy authors to imagine societies at least as strange as actually existing ones:

One of my contentions about fantasy novels, and science-fantasy and future-world novels too, is that the society of the distant future, or an alien species, or another planet, or an alternate universe, ought to be at least as complex and unlikely-seeming (to Western European/American-culture-based writers in English) as the societies, mentalities and cultures that humans have in fact produced.

This advice is all to often ignored. Although Vance, as we have seen, can't be accused of doing so.