A great mystery hangs over these two words, "the Urim and the Thummim," commonly translated "light and perfection," in the Septuagint version "manifestation and truth," and in the Vulgate "doctrine and truth."
I. The stones representing the Church that were borne upon the high-priest's breast and the high-priest's shoulders connect themselves with the Urim and Thummim. In some way or other God was pleased to reveal His will in connection with these twelve stones, in what way it is very difficult to determine. There are these possible interpretations: (1) It may be that it pleased God at certain times to throw a miraculous light upon these twelve different coloured stones, which did in some way write His mind; either by the initiatory letters, or by some signs which were familiar to the high-priest, He conveyed His will to the high-priest, that he in turn might convey it to the people. (2) It has been supposed that the stones were not made themselves the channels or media by which God conveyed His will, but that they accredited and, as it were, empowered the high-priest when he was before God, so that God, seeing him in the fulness of his priesthood, was pleased to convey His will to his mind.
II. Consider what we have that answers to Urim and Thummim, and how we should consult God and obtain our answers. (1) In prayer we should pray consultingly, in reading read consultingly. (2) In consulting God we must honestly make up our minds to follow God's guidance. (3) If we are to attain Urim and Thummim in our consultations with God, we must do it through priesthood in the recognition of the priesthood of the Lord Jesus Christ.
III. There are many ways in which God may give us the Urim and Thummim to direct our steps: (1) by a light breaking on some passage of the Bible; (2) by the Spirit of God illumining our own minds.
J. Vaughan, Meditations in Exodus,p. 54.
Reference: Exodus 28:30. J. Irons, Thursday Penny Pulpit,vol. viii., p. 167.