chair of st. peter

Today, Feb. 22, 2019, the Church celebrates the Feast of the Chair of St. Peter. What is this, basically an ancient, ornamental chair located in the apse of St. Peter's Basilica behind the famous altar. What does it represent spiritually? It is a symbol of the mission of Peter and his Successors to tend Christ's flock (as mentioned in today's first reading). The Psalm today "The Lord is My Shepherd" takes up the theme of the day of God being our (members of the flock) ultimate shepherd; which leads right into the Gospel where Jesus declares Peter the Rock on which he will build his Church.