Gregory the Great — as excerpted in the Catena Aurea on Matthew 2:10-11

“(ubi sup.) Something further may yet be meant here. Wisdom is typified by gold; as Solomon saith in the Proverbs, A treasure to be desired is in the mouth of the wise. (Prov. 21:20.) By frankincense, which is burnt before God, the power of prayer is intended, as in the Psalms, Let my speech come before thee as incense. (Ps. 141:2.) In myrrh is figured mortification of the flesh. To a king at his birth we offer gold, if we shine in his sight with the light of wisdom; we offer frankincense, if we have power before God by the sweet savour of our prayers; we offer myrrh, when we mortify by abstinence the lusts of the flesh.”