Seeing the wind (βλεπων τον ανεμον). Cf. Exodus 20:18 and Revelation 1:12 "to see the voice" (την φωνην). "It is one thing to see a storm from the deck of a stout ship, another to see it in the midst of the waves" (Bruce). Peter was actually beginning to sink (καταποντιζεσθα) to plunge down into the sea, "although a fisherman and a good swimmer" (Bengel). It was a dramatic moment that wrung from Peter the cry: "Lord, save me" (Κυριε, σωσον με), and do it quickly the aorist means. He could walk on the water till he saw the wind whirl the water round him.