A few days ago we heard an account of the confession of faith by Peter at Caesarea-Philippi which did not include the response which appears only in the Gospel According to Matthew. It may be that the references to "rock" and "keys" go back to Old Testament references to the temple foundation and the keys to the temple [Isaiah 22;22]. Matthew was writing for a primarily Jewish-Christian community. Furthermore, Matthew muddies the water a little when a similar grant of authority is given to the other disciples at 18:18. What is clear is that Peter is confirmed in his leadership among the apostles. It is that leadership, passed down in succession to the present day that is being celebrated in the feast of The Chair of St. Peter.
We are accustomed to the use of the word "chair" to mean the person in charge of a meeting: "The Chair recognizes so and so, etc." But this feast celebrates more than the power of the papacy. It is a celebration of the unity of faith in our highly diverse Catholic tradition. An overemphasis on power can result in a loss of the vision of unity in the Body of Christ. The power itself can be distorted when one forgets that the power is one of service [John 13:1-20] to the unity of faith. Pope St. John Paul II pointed to this in his encyclical Ut unum sint when he recognized that the role of primacy is capable of broader interpretation than previously understood.
The Chair of St.Peter the Apostle has been occupied over the centuries by a wide range of leaders, but it is a chair built by Christ to serve the People of God. AMEN