Gregory the Dialogist

And hence in the Song of Songs it is said to Holy Church by the voice of the bridegroom, "Thy two breasts are like two twin kids of the she goat, which feed among the lilies, until the day breathe, and the shadows incline." For what are the two breasts, except the two peoples coming from Jewry and from among the Gentiles, who are implanted in the body of Holy Church, by the purpose of wisdom, upon the secret of the heart. …

Morals on the Book of Job, Book 24.17 ↗

Bede

Those who are fed among the lilies, etc. The holy teachers are nourished by the pure and resplendent flowers of the divine Scriptures, and lest the milk of salvific doctrine, with which they feed the little ones, should lack, they always read in the writings of the Fathers what they ought to achieve, how they should teach, and they satisfy their hearts as though with vital sap, and this until the end of the world. …

Commentary on the Song of Songs ↗

Robert of Tombelaine

By the two breasts, two orders of preachers are designated: one in circumcision, the other in uncircumcision. They are fittingly called like two fawns of a doe, because they are children of the Synagogue and feed on the mountains of contemplation. They are called twins because they preach in harmony and think in harmony. …

Commentary on the Song of Songs, Chapter 4 ↗