Variously known as the Chronographer of 354 or the Philocalian Calendar, this fourth century calendar contains many listings of events that occurred in Rome during the third and fourth centuries of the Christian era. Besides the calendar being the earliest reference to December 25 as the date for Christmas, under the heading for February 22, you find this Latin entry: Natale Petri di San Pietro. Thus, the feast of the Chair of Saint Peter was observed at least as early as the fourth century.
In his book Holiness is Always in Season, the late Pope Benedict XVI wrote, “So what was the ‘Chair’ of St Peter? Chosen by Christ as the ‘rock’ on which to build the Church (cf. Mt 16:18), he began his ministry in Jerusalem, after the Ascension of the Lord and Pentecost. The Church’s first ‘seat’ was the Upper Room, and it is likely that a special place was reserved for Simon Peter in that room where Mary, Mother of Jesus, also prayed with the disciples” (p.65). This day is not just about apostolic succession in respect to the Pope and the bishops. Among the lay faithful, this feast symbolizes an unspoken confidence that the Church of Jesus does not change from age to age; that the truths of the Gospel still form the basis of the faith; that these eternal truths are reflected in every Catholic parish and in every Mass. It is a confidence that the Supreme Pontiff, as the Shepherd of shepherds adheres to and will never deny the precepts and principles of the Church of Christ.
All states of life in the world have to firmly believe that, from the highest to the lowest, are all part of the mystical body of Christ, a holy people, a holy priesthood. In the late fourth century, St. Jerome wrote this to Pope Damasus I, “I follow no leader but Christ and join in communion with none but Your Blessedness, that is, with the chair of Peter. I know that this is the rock on which the Church has been built. Whoever eats the Lamb outside this house is profane. Anyone who is not in the Ark of Noah will perish when the flood prevails.”
Excerpted from D.D. Emmons. “The Throne of Truth: What is the feast of the Chair of St. Peter? http://www.simplycatholic.com.
Nature and dignity 