And God said moreover unto Moses,
Thus shall you say unto the children of Israel, The LORD God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me unto you: this is my name forever, and this is my memorial unto all generations.
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Ambrose of Milan
For God and Lord is a name of majesty, a name of power, even as God himself says, “The Lord is my name,” and as in another place the prophet declares, “The Lord almighty is his name.” He is God, therefore, and Lord, either because his rule is over all or because he beholds all things and is feared by all without exception. .
What does it mean then that later on he gave himself another name, where it says, “And the Lord said to Moses, I am the God of Abraham, the God of Isaac and the God of Jacob: this is my name forever”? How is it that there I am called this name that shows “I am,” and lo and behold here is another name: “I am the God of Abraham, the God of Isaac and the God of Jacob”? It means that while God is indeed unchangeable, he has done everything out of mercy, and so the Son of God himself was prepared to take on changeable flesh and thereby to come to man’s rescue while remaining what he is as the Word of God. Thus he who is clothed himself with mortal flesh, so that it could truly be said, “I am the God of Abraham, the God of Isaac and the God of Jacob.”
Memorial. By this title he is still known among Christians. (Menochius)
Hitherto God had generally been called Elohim. But now he assumes the incommunicable name (Tirinus) consisting of four vowels, Jod, He, Vau, He, Jehovah, the essence, or OWN, a word which the Greek Scriptures leave undeclined, to denote the unchangeable nature of the Deity. The word has been pronounced Jehovah by the moderns, and by the ancients Jevo, Jao, Jave (Haydock)