Gregory the Dialogist : It should be known that just as a garment is woven on two beams, namely the upper and the lower, so charity is held in two commandments, that is, in the love of God and of neighbor. For it is written: "You shall love the Lord your God with all your heart, and with all your soul, and with all your strength; and your neighbor as yourself." Therefore whoever takes care to have a wedding garment at the wedding must keep these two commandments of charity. For this is why, in the prophet Ezekiel, the vestibule of the gate of that city situated on the mountain is measured at two cubits, because surely the entrance to the heavenly city is not opened to us if in this Church, which is called a vestibule because it is still outside, the love of God and neighbor is not maintained. This is why scarlet twice-dyed is commanded to be woven into the curtains of the tabernacle. You are, brothers, you are the curtains of the tabernacle, who veil heavenly secrets in your hearts through faith. But twice-dyed scarlet must be in the curtains of the tabernacle. For scarlet has the appearance of fire. And what is charity, if not fire? But this charity must be twice-dyed, so that it may be dyed through the love of God, and dyed through the love of neighbor. — 40 Homilies on the Gospels, Homily 38