Moses and Aaron tried to get the attention of the king. He refused to let the people go. Pharaoh thought his kingly power would stop God, but God has more power than we do. We live in this world and think we have power, but, God is in control.
The Psalm says that God is awesome, that he cuts off the spirit of Princes and inspires fear in the Kings of the Earth.
Do you remember who is in control? Do you humble yourself before him?