John 8:58

Jesus said, &c. That is, I am God. The word am denotes eternity, which is ever present, and has no past or future. I am eternal, immutable, and ever the same. So S. Augustine, Bede, S. Gregory. I as God exceed the age of Abraham not by fifty years, but by infinite durations of years. For as Tertullian (de Trinit.) says, unless He had been God, He could not, as being descended from Abraham, have been before him. Hear S. Augustine on this passage, " Before Abraham was made, that refers to human nature, but I am pertains to the Divine Substance; was made (Vulg.), because Abraham was a creature. He said not, 'Before Abraham was, I am,' but Before Abraham was made, I am. Nor did He say, 'Before Abraham was made, I was made.' For in the beginning God made heaven and earth; for in the beginning was the Word. Before Abraham was made, I am. Acknowledge the Creator, distinguish the creature. He who spake was made of the seed of Abraham; and in order that Abraham might he made, He was (existed) before Abraham."