This painting is part of an altarpiece, the main panel of which depicts The Virgin & Child. This section shows Saint Peter; other parts of the altarpiece show Saints Philip, John the Evangelist & John the Baptist. Peter was a fisherman when Jesus invited him to join him & become a 'fisher of men'. He was originally called Simon but Jesus changed his name to Peter, meaning 'rock', to signify that he was the founder of the church. Peter was one of the first apostles to perform baptisms & miracles & is seen here holding the keys to Heaven.