Urim and Thummim
The Urim and Thummim (Hebrew: אוּרִים ʾŪrīm, "lights" and תֻּמִּים Tummīm, "perfections") are elements of the hoshen, the breastplate worn by the High Priest attached to the ephod. They are connected with cleromancy (divination by casting lots). Most scholars suspect that the phrase refers to a set of two objects used by the high priest to answer a question or reveal the will of God.
The Urim and the Thummim first appear in the Biblical verse Exodus 28:30, where they are named for inclusion on the breastplate to be worn by Aaron in the holy place. Other books, especially 1 Samuel, describe their uses. The chronologically earliest passage in the Bible mentioning the Urim and Thummim, according to textual scholars, is in the Book of Hosea, where it is implied, by reference to the Ephod, that the Urim and Thummim were fundamental elements in Judaism, in the mid 8th century BC.
Form
The Book of Exodus portrays the Urim and Thummim as being put into the sacred breastplate, worn by the high priest over the Ephod. There is no description of the form of the Urim and Thummim in the passage describing the high priest's vestments. Nevertheless, the passage does describe them as being put into the breastplate, which scholars think implies they were objects put into some sort of pouch within it, and then, while out of view, one (or one side, if the Urim and Thummim was a single object) was chosen by touch and withdrawn or thrown out. Since the Urim and Thummim were put inside this pouch, they were presumably small and fairly flat, and were possibly tablets of wood or of bone. In this respect, they may have been similar to nordic runes.
The Talmudic rabbis argued that Urim and Thummim were not objects, but words written on the sacred breastplate.
Function
In all but two cases (1 Samuel 10:22 and 2 Samuel 5:23), questions posed to the Urim and Thummim are effectively answered by a simple "yes" or "no."
1 Samuel 14:41 describes an attempt to identify a sinner by repeatedly splitting the people into two groups and casting lots to identify which group contains the sinner. A previous verse uses a phrase "inquired of God," which implies that the inquiry was performed through cleromancy, and that Urim and Thummim were the names of the objects being cast.
In order for the Urim and Thummim to give an answer, it was first necessary for the individual to stand facing the fully dressed high priest, and vocalise the question briefly and in a simple way, though it was not necessary for it to be loud enough for anyone else to hear it. The High Priest would stand facing the Ark of the Covenant with the inquirer behind him, facing the Priest's back. After the inquirer asked his question, the Holy Spirit would immediately overcome the Priest and he would see the letters protruding in a prophetic vision.
Most of the Talmudic rabbis, and Josephus, following the belief that Urim meant "lights," argued that the rituals involving Urim and Thummim involved questions being answered by great rays of light shining out of certain jewels on the breastplate as a form of scrying; each jewel was taken to represent different letters, and the sequence of lighting thus would spell out an answer (though there were 22 letters in the Hebrew alphabet, and only 12 jewels on the breastplate).
History of use
Consulting the Urim and Thummim was permitted for determining territorial boundaries, and was required, in addition to permission from the king or a prophet, if there was an intention to expand Jerusalem or the Temple in Jerusalem. The classical rabbinical writers argued that the Urim and Thummim were only permitted to be consulted by very prominent figures such as army generals, the most senior of court figures, and kings, and the only questions which could be raised were those which were asked for the benefit of the people as a whole.
Babylonian captivity
Although Josephus argues that the Urim and Thummim continued to function until the era of the Maccabees, Talmudic sources are unanimous in agreeing that the Urim and Thummim stopped functioning much earlier, when Jerusalem was sacked by the Babylonians. In a passage from the part of the Book of Ezra which overlaps with the Book of Nehemiah, it is mentioned that individuals who were unable to prove that they were descended from the priesthood before the Babylonian captivity began, were required to wait until priests in possession of Urim and Thummim were discovered; this would appear to confirm the statements in the Talmud that the Urim and Thummim had by then been lost.
Since the priestly source does not appear to know what the Urim and Thummim looked like, and there is no mention of the Urim and Thummim in the deuteronomic history beyond the death of David, scholars suspect that use of them decayed some time before the Babylonian conquest, probably as a result of the growing influence of prophets at that time.
Maimonides states that in the Second Temple the Urim and Thummim actually existed but no longer functioned in the practical sense since the priests no longer possessed the Holy Spirit. Rabbi Abraham ben David disagrees and maintains that during that era, the Urim and Thummim were completely absent.
In Islam
According to Islamic sources, there was a similar form of divination among the Arabs before the beginning of Islam. There, two arrow shafts (without heads or feathers), on one of which was written "command" and the other "prohibition" or similar, were kept in a container, and stored in the Kaaba at Mecca; whenever someone wished to know whether to get married, go on a journey, or to make some other similar decision, one of the Kaaba's guardians would randomly pull one of the arrow shafts out of the container, and the word written upon it was said to indicate the will of the god concerning the matter in question. Sometimes a third, blank, arrow shaft would be used, to represent the refusal of the deity to give an answer.
This practice is called rhabdomancy, after the Greek roots rhabd- "rod" and -mancy.
Latter Day Saints
Joseph Smith, founder of the Latter Day Saint movement, said that he used interpreters in order to translate the Book of Mormon from the golden plates. In early accounts, Smith described the interpreters as "spectacles," described as two transparent stones set in silver bows. The earliest association of the spectacles with the biblical term "Urim and Thummim" occurred in 1833 and Smith appears to have adopted the term in subsequent descriptions.
The Urim and Thummim were said to have been found with the golden plates, a breastplate (to which the silver bows were attached in some descriptions), and the Sword of Laban. Smith's mother, Lucy Mack Smith, described these Urim and Thummim as being like "two smooth three-cornered diamonds." Smith and others also referred to individual seer stones also associated with Smith's dictation of the Book of Mormon as Urim and Thummim, although his wife, Emma Smith, in her later accounts distinguished between the seer stones and the Urim and Thummim.
Smith also said he used the Urim and Thummim to assist him in receiving other divine revelations, including some of the sections of the Doctrine and Covenants and portions of the Joseph Smith Translation of the Bible. Only Oliver Cowdery is claimed to have attempted to use them to receive his own revelation. Latter Day Saints believe that Smith's Urim and Thummim were functionally identical to the biblical Urim and Thummim.