The High Priests, of the Old Testament, primarily relied on 3 forms of divine communication; Dreams, Prophetical Utterances, and Urim & Thummim in seeking manifestations of the divine will. It is believed that these High Priests wore an Ephod (garment , modern day vestment) and over top of the Ephod was placed a breastplate. The breastplate contained 12 gemstones representing the 12 Tribes of Israel. Urim and Thummim (pronounced Tumim/Tummim in modern day Hebrew) were placed in a pouch which either attached directly to the Ephod or were inserted in the breastplate.
Little is known about the material composition of Urim and Thummim but some believe that they could have been stones, gemstones, bone or wood. Urim, known as light or to give light, would bring to light the guilt of an accused person; while Thummim, known as completeness, perfection, or innocence would establish the innocence of the accused. Urim was generally seen as the "No" while Thummim was interpreted as a "Yes" in general queries that the High Priests would ask of in seeking a divine communication.
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