You shall place on the breastplate of judgment ‘disclosure’ and ‘truth,’ (τὴν δήλωσιν καὶ τὴν ἀλήθειαν) and it will be on Aaron’s chest when he enters into the holy place before the Lord.
That’s how the Septuagint says it. The Vulgate is similar:
You shall put on the oracle of judgment ‘instruction’ and ‘truth,’ (doctrinam et veritatem) which will be on Aaron’s chest when he enters the presence of the Lord.
I like the idea of Aaron entering the presence of the Lord with the words disclosure and truth written on his clothing, but is this what the text is describing?
In Hebrew, these words are the mysterious Urim and Thummim (אֶת־הָאוּרִים וְאֶת־הַתֻּמִּים). I’ve always thought of these things as a type of dice or coins with which one can “cast lots” to make a decision. A lot of the theories you find in the commentaries swirl around similar ideas. After reviewing several options, Jacob Milgrom concludes,
Nonetheless, this theory, like those just discussed, can at best be considered only attractive speculation. The riddle of the Urim and Thummim still awaits resolution (Anchor Yale Bible Commentary, Leviticus 1–16, p. 511).
Thinking about a priest walking into the presence of God with “disclosure” and “truth” on his chests reminds me of the tenor of the psalms. The psalmist enters the presence of God, discloses his thoughts and feelings, and asks for the Lord to act faithfully and true on his behalf.
Hey! You love truth! Things that are unknown and the secrets of your wisdom you make known to me!
ἰδοὺ γὰρ ἀλήθειαν ἠγάπησας, τὰ ἄδηλα καὶ τὰ κρύφια τῆς σοφίας σου ἐδήλωσάς μοι.
The psalmist bears his soul to the Lord, and the Lord reveals his wisdom to the psalmist.
Anyway, it’s interesting to ponder these ancient rendering of Urim and Thummim.