The Vigil of St. Matthias, the Apostle

5_14_matthiasCommemoration is made, in the Mass of St. Peter Damian, of the vigil or eve of St. Matthias, Apostle, whose feast is kept on February 24, except in leap year; at that time it is kept on February 25.
This vigil was instituted by St. Pius V in order to raise the feast of St. Matthias to the same dignity as that of the feast of the other apostles.
(Source: Fr. Lasance, The New Roman Missal)

St. Peter Damian

feb-21-st-peterdamia_351238This saintly Bishop of Ostia, selected as advisor by seven popes in succession was a fearless and distinguished son of the Order of St. Benedict, who, in the Eleventh Century – a very turbulent period marked by antipopes, heresies, and a lamentable relaxation of the religious spirit – was like a column of fire guiding the faithful along the narrow path of the Cross of Christ that leads in safety to heaven. He passed from this life to God on February 22, 1072, but because of the feast of the Chair of Peter, his yearly commemoration takes place today. Leo XII ordered that his Office which was at first observed only by the Benedictines should be extended to the Universal Church. (Source: Butler’s Lives of the Saints)