How well did our spiritual ancestors actually know God? At the beginning of our Torah portion, Va-eira, God seems to suggest the relationship wasn't quite as intimate as we would have thought.
"God spoke to Moses and said to him: "I am the Eternal [YHVH]. I appeared to Abraham, Isaac, and Jacob as El Shaddai, but I did not make Myself known to them by My name YHVH" (Exodus 6:2-3).
The patriarchs had known God by one name, but apparently, not by the name through which God will be known to Moses, to the Israelites in the later books of the Bible, or to Jews today. It's a surprising statement. The patriarchs, after all, are understood by Jewish tradition to have been particularly intimate with God. In the Amidah prayer, we invoke their names when we address God - God of Abraham, God of Isaac, God of Jacob - precisely because of the strength of their relationships with God. And now, we find out that they didn't even know one of God's most important names?
If we open up the Book of Genesis, we find things a little more complicated than our verse might suggest on its surface. The name Eternal appears all over Genesis; the patriarchs are quite familiar with Eternal as a name of God. Abraham refers to God as Eternal when directly addressing God (see, for example, Genesis 15:2) and when speaking to others about God (Genesis 14:22). Sarah also uses the name Eternal when she speaks to Abraham about God (Genesis 16:2). And Isaac and Jacob use the name as well (See, for example, Genesis 26:25 and Genesis 28:16).