Urim and Thummim
Hebrew term that means “Lights and Perfections.” An instrument prepared of God to assist man in obtaining revelation from the Lord and in translating languages. See Ex. 28:30; Lev. 8:8; Num. 27:21; Deut. 33:8; 1 Sam. 28:6; Ezra 2:63; Neh. 7:65; JS—H 1:35.
Using a Urim and Thummim is the special prerogative of a seer, and it would seem reasonable that such instruments were used from the time of Adam. However, the earliest mention is in connection with the brother of Jared (Ether 3:21–28). Abraham used a Urim and Thummim (Abr. 3:1–4), as did Aaron and the priests of Israel, and also the prophets among the Nephites (Omni 1:20–21; Mosiah 8:13–19; 21:26–28; 28:11–20; Ether 4:1–7). There is more than one Urim and Thummim, but we are informed that Joseph Smith had the one used by the brother of Jared (Ether 3:22–28; D&C 10:1; 17:1). (See Seer.) A partial description is given in JS—H 1:35. Joseph Smith used it in translating the Book of Mormon and in obtaining other revelations.
This earth in its celestial condition will be a Urim and Thummim, and many within that kingdom will have an additional Urim and Thummim (D&C 130:6–11).