As we have seen this year, the number of the Sundays after Pentecost may exceed twenty-four, and go as far as twenty-eight, according as Easter is each year more or less near to the vernal equinox. But the Mass here given is always reserved for the last; and the intervening ones, be their number what it may, are taken from the Sundays after the Epiphany, which, in that case, were not used at the beginning of the year. This, however, does not apply to the Introit, Gradual, Offertory, and Communion, which are repeated from the twenty-third Sunday. We have seen how that Mass of the twenty-third Sunday was regarded, by our forefathers, as really the last of the cycle. Abbot Rupert has given us the profound meaning of its several parts. According to the teaching we have already pondered over, the reconciliation of Juda was shown us as being, in time, the term intended by God: the last notes of the sacred liturgy blended with the last scene of the world’s history, as seen and known by God. The end proposed by eternal Wisdom in the world’s creation, and mercifully continued, after the fall, by the mystery of Redemption, has now (we speak of the Church’s year and God’s workings) been fully carried out. This end was no other than that of divine union with human nature, making it one in the unity of one only body. Now that the two antagonistic people, Gentile and Jew, are brought together in the one same new Man in Christ Jesus their Head, the two Testaments, which so strongly marked the distinction between the ages of time, the one called the old, the other the new, fade away, and give place to the glory of the eternal Alliance. Hence, it was there that mother Church formerly finished her liturgical year. She was delighted at what she had done during all the past months; that is, at having led her children, not only to have a thorough appreciation of the divine plan, which she had developed before them in her celebrations, but moreover, and more especially, to unite them themselves, by a veritable union, to their Jesus, by a real communion of views, and interests, and loves. On this account, it used to be that she did not revert again to the second coming of the God-Man and the last judgment, two great subjects which she had proposed for her children’s reflections at the commencement of the purgative life, that is, in her season of Advent.

It is only a few centuries ago that, with a view of giving to her year a conclusion more defined and intelligible to the faithful of these comparatively recent times, she chose to conclude the cycle with the prophetic description of the dread coming of her Lord, which is to put an end to time, and to open eternity. From time immemorial, St. Luke had had the office of announcing, in Advent, the approach of the last judgment; the evangelist St. Matthew was selected for this its second, and more detailed, description, on the last Sunday after Pentecost. . . . Several times during Advent we meditate on the circumstances which are to accompany the last coming of Christ our Lord; and in a few days the same great teachings will be again brought before us, filling our souls with a salutary fear. May we, then, be permitted on this last Sunday of our liturgical year to address ourselves in a prayer of desire and praise to our adorable Lord and King, the solemn hour of whose judgment is to be the consummation of His work, and the signal of His triumph.

Commentary from The St. Andrew Daily Missal (1954 ed.) by Dom Gaspar Lefevre, O.S.B., and The Liturgical Year by Dom Prosper Guéranger, O.S.B.