If it were not Sunday...
today would be the feast of The Chair of St. Peter, when the Church commemorates the establishment of the see of Rome.
"Deeply do I feel, ever will I protest, for I can appeal to the ample testimony of history to bear me out, that, in questions of right and wrong, there is nothing really strong in the whole world, nothing decisive and operative, but the voice of him, to whom have been committed the keys of the kingdom and the oversight of Christ's flock. The voice of Peter is now, as it ever has been, a real authority, infallible when it teaches, prosperous when it commands, ever taking the lead wisely and distinctly in its own province, adding certainty to what is probable, and persuasion to what is certain. Before it speaks, the most saintly may mistake; and after it has spoken, the most gifted must obey." - Venerable John Henry Newman, C.O. Cathedra Sempiterna

It would also be the feast of one of the great penitents, St. Margaret of Cortona.