"I am coming to you in a dense cloud, so that when the people hear me speaking with you, they may always have faith. On the morning of the third day there were peals of thunder and ligthning, and a heavy cloud over the mountain, a very loud trumpet blast, so that all the people trembled. Mount Sinai was all wrapped in smoke, for the Lord came down upon it in fire. The smoke rose from it as though from a furnace, and the whole mountain trembled violently." (Exodus 19)