And God said unto Moses,
I AM THAT I AM:
and he said,
Thus shall you say unto the children of Israel, I AM has sent me unto you.
All Commentaries on Exodus 3:14 Go To Exodus 3
Augustine of Hippo
AD 430
Magnificently and divinely, therefore, our God said to his servant: “I am that I am,” and “You shall say to the children of Israel, He who is sent me to you.” For he truly is because he is unchangeable. For every change makes what was not, to be. Therefore he truly is, who is unchangeable; but all other things that were made by him have received being from him each in its own measure.