When love has entirely cast out fear, and fear has been transformed into love, then the unity brought us by our savior will be fully realized, for all men will be united with one another through their union with the one supreme Good. They will possess the perfection ascribed to the dove, according to our interpretation of the text: One alone is my dove, my perfect one. She is the only child of her mother, her chosen one. Our Lord’s words in the gospel bring out the meaning of this text more clearly. After having conferred all power on his disciples by his blessing, he obtained many other gifts for them by his prayer to the Father. Among these was included the greatest gift of all, which was that they were no longer to be divided in their judgment of what was right and good, for they were all to be united to the one supreme Good. As the Apostle says, they were to be bound together with the bonds of peace in the unity that comes from the Holy Spirit. They were to be made one body and one spirit by the one hope to which they were all called. We shall do better, however, to quote the sacred words of the gospel itself. I pray, the Lord says, that they all may be one; that as you, Father, are in me and I am in you, so they also may be one in us.
From a homily on the Song of Songs by Saint Gregory of Nyssa, bishop