The third, that with the greatest vigor he commanded that his chair should be set on the shore, when the tide began to rise. And then he spoke to the rising sea saying “You are part of my dominion, and the ground that I am seated upon is mine, nor has anyone disobeyed my orders with impunity. Therefore, I order you not to rise onto my land, nor to wet the clothes or body of your Lord”. But the sea carried on rising as usual without any reverence for his person, and soaked his feet and legs. Then he moving away said: “All the inhabitants of the world should know that the power of kings is vain and trivial, and that none is worthy the name of king but He whose command the heaven, earth and sea obey by eternal laws”. Therefore King Cnut never afterwards placed the crown on his head, but above a picture of the Lord nailed to the cross, turning it forever into a means to praise God, the great king. By whose mercy may the soul of King Cnut enjoy peace.
http://faculty.history.wisc.edu/sommerv ... 0Waves.htm