Exodus 28:30

And thou shalt put in the breastplate of judgment, in the pocket formed by its fold, the Urim and the Thummim (light and perfection; or revelation and truth); and they shall be upon Aaron's heart when he goeth in before the Lord; and Aaron shall bear the judgment of the children of Israel upon his heart before the Lord continually, that is, the sentence of salvation, or righteousness, and the sentence of judgment; as the high priest he was the mediator between God and the people. Every high priest appearing before the Lord with the Urim and Thummim thereby became the advocate of the people, and usually received from the Lord such illumination as served to protect the children of Israel in their promised rights, Numbers 27:21. Christ is our High Priest. He is our Advocate with the Father; He reveals to us God's light and truth, God's gracious and good will toward us, by which we receive counsel and comfort in dark days. The Word of the Lord is a lamp unto our feet and a light upon our path.