Mk 6:45-52
45[Jesus] made his disciples get into the boat and precede him to the other side toward Bethsaida, while he dismissed the crowd. 46And when he had taken leave of them, he went off to the mountain to pray. 47When it was evening, the boat was far out on the sea and he was alone on shore. 48Then he saw that they were tossed about while rowing, for the wind was against them. About the fourth watch of the night, he came toward them walking on the sea. He meant to pass by them. 49But when they saw him walking on the sea, they thought it was a ghost and cried out. 50They had all seen him and were terrified. But at once he spoke with them, “Take courage, it is I, do not be afraid!” 51He got into the boat with them and the wind died down. They were [completely] astounded. 52They had not understood the incident of the loaves. On the contrary, their hearts were hardened.
TAKE COURAGE, IT IS I: Jesus, alone on the mountain while praying, looks at his disciples far out in the sea, in a boat tossed about by the waves. He comes to them on the sea, meaning “to pass by them.” For Mark, the event is a theophany, a manifestation of the transcendent Lord, alluding to the Lord of Israel who “passed by” at Sinai before Moises (Ex 33:19) or at Horeb before Elijah (1 Kgs 19:11). He is the one “who treads upon the crests of the sea” (Jb 9:8). The appearance of Jesus over the waters is therefore a reminder of the apparitions of God to Israel and suggests a manifestation of the divine power residing in Jesus.
However, the disciples react to Jesus’ appearance with terror, mistaking him to be a water spirit. It was popularly believed then that the spirits of the night brought disaster to those they encountered. When Jesus allays the fears of the disciples with a summons to courage, he says, “It is I.” This can be understood as a normal statement of identity (“It is I, Jesus”), but it can also possess a deeper significance as the recognized formula of God’s self-revelation. God gives his name to Moses in the burning bush: “I am that I am” (Ex 3:14). Thus, the walking upon the water and the emphatic “I” favor a theophanic interpretation: Jesus is revealed as possessing divine power.
Moreover, the admonition to “take courage” is an integral part of the divine formula of self-revelation. God promises to Israel: “Fear not, for I have redeemed you… When you pass through the water, I will be with you; in the rivers you shall not drown… For I am the Lord, your God, the Holy One of Israel, your savior” (Is 43:1-3).