After the miraculous feeding of the multitude Jesus put the disciples in a boat and made them go to the other side of the lake—it was the first time since they were called that Jesus would not physically be with them. So Jesus dismissed the crowd and went off alone to pray, and the disciples set sail for the other side.
The lake—indeed all waters and seas—were considered by the people in Jesus’ time to be places of spiritual disorder and chaos. To the mind of the gospel writer, to be at sea is to encounter danger, exposing oneself to spiritual assault and even the threat of death. And so the long night wore on, fraught with spiritual doubts and dangers, while a strong wind battered the boat pushed the disciples further and further from the shoreline, further from their Master.
Then suddenly, in the coldest, darkest part of the night, Jesus came to them again, his appearance generating in Peter (and all of them) an whole spectrum of doubts, fears, awe, worship, and a taste of the power that will lead to resurrection. It is a scene that believers will reenact again and again throughout the history of the church—as we encounter a world of evil and call to God from that turbulent place between our doubts and fears.