Exodus — Chapter 28

And take thou unto thee Aaron thy brother and his sons with him from among the children of Israel, that he may minister to me in the priest's office. Lapide treats the Aaronic priesthood as a figure of the Christian priesthood. Aaron represents Christ as High Priest; his sons represent the ministerial priesthood of the New Covenant. The vestments prescribed in this chapter are allegorized: the ephod with its two onyx stones bearing the names of the twelve tribes signifies that the priest carries the entire people before God; the breastplate with twelve precious stones signifies the twelve apostles and the whole Church borne on the heart of Christ the High Priest.

Thou shalt make the rational of judgment with embroidered work of divers colours. The rational (breastplate of judgment) worn by the high priest over his heart contained the Urim and Thummim (lights and perfections) by which God gave oracular responses. Lapide identifies the Urim and Thummim as a figure of the twofold knowledge of the priest: the Urim (lights) represents doctrinal illumination (scientia), the Thummim (perfections) represents moral integrity (justitia). The priest who carries the oracle of God must be both learned and holy.

Thou shalt make also a plate of the purest gold, wherein thou shalt grave with engraver's work: Holy to the Lord. This inscription on the golden plate worn on Aaron's forehead signifies that the whole of the priest's person, intellect, and will must be consecrated to God. Lapide notes that Aaron bore the iniquity of the holy things of the children of Israel (vers. 38)—the priest is the mediator who stands between God's holiness and the people's failures, offering sacrifice for both. This is perfectly fulfilled by Christ, who bore the iniquity of us all.