Matthew Poole's Concise Commentary
Exodus 28:30
The words Urim and Thummim confessedly signify light, or illuminations and perfections, which may be understood either of two differing things, the one noting the knowledge, the other the perfection, to wit, of virtues and graces, which were required in the high priest, and which were in Christ in an eminent degree, and from him alone communicated to his people; or of one and the same thing, noting perfect light or illumination, by a figure called hendyadis, oft used in Scripture, as Deuteronomy 16:18 Matthew 4:16, compared with Job 10:21 1 Thessalonians 3:5 Acts 17:25, compared with Genesis 2:7. Which may seem probable,
1. Because the great use of this instrument was to give light and direction in dubious and difficult cases, and not to confer any other perfection upon any person.
2. Because sometimes both these words and things are expressed only by one of them, and that is by Urim, Numbers 27:21 1 Samuel 28:6, which signifies lights. And the name seems to be given from the effect, because hence the Israelites had clear light, and perfect or certain direction in dark and doubtful matters. But the great question is, what this Urim and Thummim was, and in what manner God answered by it; which God having on purpose concealed from us, and not set down the matter or form of it, as he hath done of all the other particulars, it may seem curiosity and presumption for men solicitously to inquire, and positively to determine. Many conceive it was nothing else but the twelve precious stones, wherein the names of the twelve tribes were engraven, and that the answer of God was composed out of those letters which either show more brightly, or thrust themselves further outward, than the rest did; which seems a frivolous and ungrounded conjecture, both because all the letters of the alphabet were not there, and so all answers could not be given by them; and because it was shut up within the duplicature of the breastplate, and therefore could not be seen by the high priest; and there is not a word to signify that he was to take it out thence, and look upon it, but rather the contrary is evident. And that this Urim and Thummim are not the same thing with those twelve stones may be easily proved:
1. Because the stones were set and engraven in the breastplate, Exodus 28:17,21, this was only put into it, which is a word of quite different and more loose and large signification, and therefore probably doth not design the same thing.
2. It is not likely that in such a brief account of the sacred utensils the same command would be repeated again, especially in more dark and general words than it was mentioned before. And how could Moses now put it in, when the workmen had fastened it there before? or why should he be required to put it in the breastplate, when it was fastened to it already, and could not without violence be taken from it?
3. Because the stones were put in by the workmen, Exodus 39:10, the Urim and Thummim by Moses himself, Leviticus 8:8. It is objected, that where the stones are mentioned there is no mention of Urim and Thummim, as Exo 29, and that where the Urim and Thummim are mentioned there is no mention of the stones, as Leviticus 8:8, which shows they were one and the same thing. But that is not necessary, and there is an evident reason of both those omissions; of the former, Exo 39, because he mentions only those things which were made by the workmen, whereas the Urium and Thummim seems to have been made immediately by God, or by Moses with God's direction; of the latter, Le 8, because the stones are implied in the breastplate as a part of it, and being fastened to it, whereas there he only mentions what was put in by Moses himself. There are other conjectures, as that it; as the name Jehovah, or some visible representations, &c. But such conjectures are as easily denied as affirmed. It is therefore more modest and reasonable to be silent where God is silent, than to indulge ourselves in boundless and groundless fancies. It may suffice us to know that this was a singular piece of Divine workmanship, which the high priest was obliged to wear upon solemn occasions, as one of the conditions upon which God engaged to give him answers; which answers God might give to him either by inward suggestion to his mind, or by a vocal expression to his ear. But which of those ways, or whether by any other way, it is needless now to search, and impossible certainly to discover. The judgment of the children of Israel. A short speech. As the testimony is oft put for the ark of the testimony, so is the judgment here for the breastplate of judgment, i.e. that breastplate which declared the judgment, or oracle, or mind of God to the Israelites in those cases which they brought to the Lord. Before the Lord continually, i.e. at all times when he shall appear before the Lord in the holy place.