Urim and Thummim
What exactly are the “Urim and Thummim” of Aaron’s breastplate? The Torah mentions it without any further explanation.
The Aish Rabbi Replies
The Urim and Thummim (urim v’tumim) refer to a single piece of parchment which had God’s ineffable name inscribed on it (the Tetragrammaton). It was placed inside Aaron’s breastplate (choshen), between the two folds. (The breastplate consisted of a large rectangular piece of cloth doubled over. The outer fold contained 4 rows of precious stones, 3 per row. Each stone had the name of one of the Twelve Tribes etched onto it. It was worn over the High Priest’s torso. See Exodus 28:15-30.)
The Sages teach us that because of the parchment, High Priests were able to communicate prophetically with God. A great person such as a king would pose a question before the fully-vested High Priest, and if the questioner and the priest were both worthy, the letters on the breastplate stones would light up (or jut out, or arrange themselves) in a manner which would convey the response. It was used only for matters of national concern – such as for going to war or dividing the Land of Israel.
The curious name of the parchment was based on its function: it would make its words “shine” (urim relates to mai’ir – to shine), and it would “make whole” its words (tumim relates to mitamem – to make complete), meaning that its prophecies would always come true (Talmud Yoma 73b).
The Torah only hints to this function of the breastplate. In Numbers 27:21 God tells Moses that his successor Joshua would stand before Elazar the High Priest and inquire of him “the judgments of the Urim.” Also, the breastplate is generally referred to as the “breastplate of justice” (choshen mishpat), and in Exodus 28:30 the Torah states that by wearing it, Aaron would “bear the judgments” of Israel. The meaning, according to one interpretation, is that the High Priest would be responsible for receiving judgments and decisions on Israel’s behalf (Rashi there).
In the earlier books of the Prophets, there are several references to the Urim and Thummim being used for guidance in national matters, or more generally of Israel asking God directly for guidance (without mention of a prophet) and which the Sages understand was via the breastplate. See for example Judges 20:18, I Samuel 10:22, 14:37, 23:9-12, 28:6, 30:7-8, II Samuel 5:23, and 21:1.
There is another cryptic phrase which occasionally appears in the Torah and which the Sages explain refers to the Urim and Thummim: the “Keraiti and Plaiti” (e.g. II Samuel 8:18 and 20:7). The Talmud explains these terms as referring to the parchment in that they “cut” (kortim) their words (with clear-cut decisions) and they are wondrous (mufla’im) in their words (Brachot 3b).
Clearly, there was something so lofty and ethereal about the Urim and Thummim that it could not be defined with a simple word, even in as precise and expressive a language as Hebrew. It could only be described indirectly, via its function. For the Urim and Thummim did not belong in the physical world at world, and as a result, no concrete word could define its essence. Nachmanides likewise describes the parchment as “the handiwork of heaven,” and “a secret handed to Moses from the mouth of the Almighty” (commentary to Exodus 28:30).
The Second Temple lacked some of the most sacred items of the Temple of Solomon. One of them was the Urim and Thummim parchment. (According to some, the breastplate did contain the parchment but Israel was not on the spiritual level for it to function prophetically.) (Talmud Sotah 48b, Yoma 21b, Tosafot there s.v. “v’urim”, Rambam Beit HaBechira 4:1 with Ra’avad, Rashi to Exodus 28:30).