131. Arius declares that the Son of God may change and swerve. How, then, is He God if He is changeable, seeing that He Himself hath said: “I am, I am, and I change not”? St. Ambrose’ version differs in expression from the Vulg.—Ego enim Dominus et non mutor (Mal. iii. 6)—but not in substance, for Ego sum Dominus and “I am the Lord” both mean “I am He who is”—(ὁ ὢν)—which is very well represented by Ego sum, Ego sum—“I am, I am.”—Cf. Ex. iii. 14.