In order to understand the Scriptures, it is absolutely necessary to know the whole, complete Christ, that is, Head and members. For sometimes Christ speaks in the name of the Head alone … sometimes in the name of His body, which is the holy Church spread over the entire earth.
Augustine of Hippo, On the Mystical Body of Christ, in The Whole Christ: The Historical Development of the Doctrine of the Mystical Body in Scripture and Tradition (1938, 1962) by Fr. Emile Mersch, S. J., translated by John R. Kelly, S.J, Part 3 : The Doctrine of the Mystical Body in Western Tradition, Ch. 4, Augustine’s Sermons to the People, p. 419