After the voice had spoken, only Jesus was found.  They kept silent, and in those days told no one what they had seen.
Luke 9:36

"...kept silent..."  I wonder if those words were ever before or since spoken about Peter?  He was always the first to speak up with glorious affirmations of Jesus; and always the first to stick his foot in his mouth up to the knee. 

What would it take to shock him into silence?  Not the appearance of Moses and Elijah, he was still talking then.  The overshadowing cloud seemed to end that thought.  I wonder what they saw in that cloud.  Was it the same cloud that lead the Israelites through the desert,  the one Moses disappeared in to receive the commandments? 

They were fisherman, accustomed to fog, it couldn't be any ordinary cloud to bring such fear.  But then, they heard the voice of God; the voice that called Abraham to leave his home for a new land, Paul to leave his heritage to bring Jesus to the world.  The voice of God, sometimes a call to action, sometimes a call to speak, but sometimes a call to trembling silence.