Charles Ellicott Commentary Isaiah 51:15

"For I am Jehovah thy God, who stirreth up the sea, so that the waves thereof roar: Jehovah of hosts is his name." — Isaiah 51:15 (ASV)

But I am ... —Better, Seeing that I am. The fact which follows is not contrasted with that which precedes, but given as its ground. The might of Jehovah is seen in the storm-waves of the sea. It is seen not less in the fall and rise of empires.