Augustine of Hippo
Catena Aurea · Matthäusevangelium 14
And straightway Jesus constrained his disciples to get into a ship, and to go before him unto the other side, while he sent the multitudes away. And when he had sent the multitudes away, he went up into a mountain apart to pray: and when the evening was come, he was there alone. But the ship was now in the midst of the sea, tossed with waves: for the wind was contrary. And in the fourth watch of the night Jesus went unto them, walking on the sea. And when the disciples saw him walking on the sea, they were troubled, saying, It is a spirit; and they cried out for fear. But straightway Jesus spake unto them, saying, Be of good cheer; it is I; be not afraid. And Peter answered him and said, Lord, if it be thou, bid me come unto thee on the water. And he said, Come. And when Peter was come down out of the ship, he walked on the water, to go to Jesus. But when he saw the wind boisterous, he was afraid; and beginning to sink, he cried, saying, Lord, save me. And immediately Jesus stretched forth his hand, and caught him, and said unto him, O thou of little faith, wherefore didst thou doubt? And when they were come into the ship, the wind ceased. Then they that were in the ship came and worshipped him, saying, Of a truth thou art the Son of God.
(Serm. 76.) For in one Apostle, namely Peter, first and chief in the order of Apostles in whom was figured the Church, both kinds were to be signified; that is, the strong, in his walking upon the waters; the weak, in that he doubted, for to each of us our lusts are as a tempest. Dost thou love God? Thou walkest on the sea; the fear of this world is under thy feet. Dost thou love the world? It swallows thee up. But when thy heart is tossed with desire, then that thou mayest overcome thy lust, call upon the divine person of Christ.