Named Repeatedly in Scripture, Described in Detail by No One

The Urim and Thummim are named in Exodus as objects placed within the High Priest's breastplate and appear again in Numbers, Deuteronomy and the narrative books, most memorably in the account of Saul consulting them before the battle recorded in First Samuel, yet at no point does the biblical text describe their physical form, only their placement and, in a handful of narrative passages, something of how they were consulted.

Van Dam's monograph, the standard modern study devoted specifically to the subject, works through every occurrence of the pair across the Hebrew Bible and concludes that the text simply never intended to specify their appearance, treating their use as familiar enough to its original audience that no description was thought necessary, a gap modern readers experience very differently than the text's first readers evidently did.

Proposed reconstructions across the long history of Jewish and Christian commentary have ranged from a pair of engraved stones or lots read as a form of binary yes or no answer, to a more elaborate mechanism involving the breastplate's twelve tribal stones, and no single proposal has ever achieved anything close to full scholarly consensus.