score:4
He wanted to show His control over the universe. See St. Thomas Aquinas's discussion on God's divine governance in his Summa Theologica (I q. 103).
St. Bede says this about the mystical sense:
Rising up, He threatened the wind, because when He had triumphed in His resurrection, He prostrated the pride of the devil. He ordered the sea to be still, that is, in rising again, He cast down the rage of the Jews. The disciples are blamed, because after His resurrection, He chided them for their unbelief. And we also when being marked with the sign of the Lord's cross, we determine to quit the world, embark in the ship with Christ; we attempt to cross the sea; but, He goes to sleep, as we are sailing amidst the roaring of the waters, when amidst the strivings of our virtues, or amidst the attacks of evil spirits, of wicked men, or of our own thoughts, the flame of our love grows cold. Amongst storms of this sort, let us diligently strive to awake Him; He will soon restrain the tempest, pour down peace upon us, give us the harbour of salvation.