See Ambrose, de Sacramentiis 1.18, trans. Roy J. Deferrari, Saint Ambrose: Theological and Dogmatic Works, FOC 44 (Washington: Catholiv Univ. of America Press, 1963), p. 275, text in CSEL 73, p. 23; and Ignatius, Epistle to the Ephesians 18.2, trans. Kirsopp Lake, The Apostolic Fathers, Loeb Classical Library (Cambridge, MA: Harvard Univ. Press, 1912), vol. 1, pp. 191–193.