Now Moses was keeping the flock of Jethro, his father-in-law, the priest of Midian, and he led the flock to the back of the wilderness, and came to God’s mountain, to Horeb. The angel of the LORD appeared to him in a flame of fire out of the midst of a bush. He looked, and behold, the bush burned with fire, and the bush was not consumed. Moses said, “I will turn aside now, and see this great sight, why the bush is not burnt.”  Exodus 3:1-3