Changing a name in Holy Scripture is often a sign of a new calling and a new purpose. Simon here receives the name Peter, which means a rock or a cliff. This shows that Christ not only calls people, but also gives them a new identity within His plan. Simon in his natural state was an unstable person, sometimes wavering, yet the Lord saw in him the person in whom His grace would work later on. In the same way, God often sees in us not only what we are now, but what we will become by His grace. The name Peter, in essence, showed what Simon was to become by the will of God and what ministry he was to have.