וַיָּ֥שֶׂם עָלָ֖יו אֶת־הַחֹ֑שֶׁן וַיִּתֵּן֙ אֶל־הַחֹ֔שֶׁן אֶת־הָאוּרִ֖ים וְאֶת־הַתֻּמִּֽים׃
And he placed the breastplate upon him; and in the breastplate he put the Urim and the Thummim.
Read kabbalistic (mystical) interpretation of Leviticus 8:8: and classical mystical sources.