This is not one of the most ancient of the festivals generally observed by the Church, as there is no provision for it in the Lectionary of St. Jerome; but there is a Collect for it in the Sacramentary of St. Gregory, and in a German martyrology of about the same period. It comes first in order after the Festivals of the Incarnation, perhaps because St. Matthias represents the earliest independent action of the Church as that spiritual body which was to exercise the authority of Christ, and to become the substitute, in some measure, for His Visible Presence. But in the Eastern Church it is August 9th.
St. Matthias' Day was formerly changeable in Leap Year, when the intercalated day was added between February 23rd and 24th, and the 25th became the festival of St. Matthias. But at the revision of the Calendar in 1661, the intercalary day was placed at the end of the month, and the festival of St. Matthias fixed permanently to the 24th day. This is the day (VI. Kalend. Martii) appointed for the Festival in the Sacramentary of St. Gregory.
Nothing more is recorded of St. Matthias in the New Testament than that he was chosen to be an Apostle in the place of Judas Iscariot, the account of his Ordination to that high Office being given in Acts i. 15—26, the Epistle of the day throughout the world. The Eastern Gospel contains the same solemn prayer of our Lord as that does which is used in the Western Church, though taken from a different Evangelist; and the coincidence is a striking illustration of the unity of mind by which the whole Catholic Church is pervaded. It is plain also that this Gospel is intended to show that the Apostle, on whose day it is used, was as much "numbered with" the other Apostles, although ordained by men, as any of those were who were ordained by our Lord Himself; and thus illustrates the great truth, that the Great High Priest Himself declared, "As My Father hath sent Me, even so send I you."
The tradition of the Church respecting St. Matthias' Apostolic labours is, that after ministering for some years among his countrymen the Jews, he went to Cappadocia, and was eventually crucified there about the year of our Lord 64. The manner of his death was not very unlike that of the traitor Judas, but the one found the tree on which he hung the way "to his own place;" the other, his Master's own road to the Paradise of God.
Introit.—Thy friends are exceeding honourable unto me, O God : greatly is their beginning strengthened. Ps. O Lord, Thou hast searched me out and known me: Thou knowest my downsitting and mine uprising. Glory be.