Leviticus 8:8 [Moses] placed the breastpiece on [Aaron] and put the Urim and Thummim in the breastpiece.
Much scholarly time and effort has gone into trying to determine what the ‘Urim and Thummim’ meant, what they consisted of, and how they were used by the High Priest. While a fair bit of speculation must remain, it seems that they could be derived from Hebrew word roots related to ‘light’ and ‘perfection’ respectively. We are told that God used them to make ‘divine revelations’ to his people through the High Priest when important decisions needed to be made, but we are not told the mechanics of how this operated.
It is significant that ‘Urim and Thummim’ occurs only 5 times in the Old Testament – Exodus 28:30, Leviticus 8:8 and Deuteronomy 33:8, and in Ezra 2:63 and Nehemiah 7:65 – and ‘Urim’ also occurs alone without ‘Thummim’ in Numbers 27:21 and 1 Samuel 28:6. We can derive then, that this little understood or employed method for determining God’s will was eventually replaced by the divinely inspired word of the prophets, and ultimately by the Canon of the Written Word, and by the revelation of Jesus the Living Word.
In the light of all this, how thankful we should be that we have access to the inspired Scriptures; and how committed we should be to reading, and meditating upon the Scriptures as we seek to live in obedience to God’s will day by day! The Apostle Peter confidently testified, “We did not follow cleverly invented stories when we told you about the power and coming of our Lord Jesus Christ, but we were eye-witnesses of his majesty. For he received honour and glory from God the Father when the voice came to him from the Majestic Glory, saying, ‘This is my Son, whom I love; with him I am well pleased.’ We ourselves heard this voice that came from heaven when we were with him on the sacred mountain. And we have the word of the prophets made more certain, and you will do well to pay attention to it, as to a light shining in a dark place, until the day dawns and the morning star rises in your hearts. Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation. For prophecy never had its origin in the will of man, but men spoke from God as they were carried along by the Holy Spirit.” (2 Peter 1:16-21); and, “Bear in mind that our Lord’s patience means salvation, just as our dear brother Paul also wrote to you with the wisdom that God gave him. He writes the same way in all his letters, speaking in them of these matters. His letters contain some things that are hard to understand, which ignorant and unstable people distort, as they do the other Scriptures, to their own destruction.” (2 Peter 3:15-16).
And the Apostle Paul instructed Timothy, “All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the man of God may be thoroughly equipped for every good work.” (2 Timothy 3:16-17). Since God has seen fit to reveal himself to us in this clear, propositional way, let us be diligent in studying and inwardly digesting the Scriptures, and let us not be found just treating them like ‘Urim and Thummim’ in an unthinking ‘promise box’ fashion!