WHY is May called the month of Mary, and especially dedicated to her? Among other reasons there is this, that of the Church's year, the ecclesiastical year, it is at once the most sacred and the most festive and joyous portion. Who would wish February, March, or April, to be the month of Mary, considering that it is the time of Lent and penance? Who again would choose December, the Advent season—a time of hope, indeed, because Christmas is coming, but a time of fasting too? Christmas itself does not last for a month; and January has indeed the joyful Epiphany, with its Sundays in succession; but these in most years are cut short by the urgent coming of Septuagesima.
May on the contrary belongs to the Easter season, which lasts fifty days, and in that season the whole of May commonly falls, and the first half always. The great Feast of the Ascension of our Lord into heaven is always in May, except once or twice in forty years. Pentecost, called also Whit-Sunday, the Feast of the Holy Ghost, is commonly in May, and the Feasts of the Holy Trinity and Corpus Christi are in May not unfrequently. May, therefore, is the time in which there are such frequent Alleluias, because Christ has risen from the grave, Christ has ascended on high, and God the Holy Ghost has come down to take His place.
Here then we have a reason why May is dedicated to the Blessed Mary. She is the first of creatures, the most acceptable child of God, the dearest and nearest to Him. It is fitting then that this month should be hers, in which we especially glory and rejoice in His great Providence to us, in our redemption and sanctification in God the Father, God the Son, and God the Holy Ghost.
But Mary is not only the acceptable handmaid of the Lord. She is also Mother of His Son, and the Queen of all Saints, and in this month the Church has placed the feasts of some of the greatest of them, as if to bear her company. First, however, there is the Feast of the Holy Cross, on the 3d of May, when we venerate that Precious Blood in which the Cross was bedewed at the time of our Lord's Passion. The Archangel St. Michael, and three Apostles, have feast-days in this month: St. John, the beloved disciple, St. Philip, and St. James. Seven Popes, two of them especially famous, St. Gregory VII. and St. Pius V.; also two of the greatest Doctors, St. Athanasius and St. Gregory Nazianzen; two holy Virgins especially favoured by God, St. Catherine of Sienna (as her feast is kept in England), and St. Mary Magdalen of Pazzi; and one holy woman most memorable in the annals of the Church, St. Monica, the Mother of St. Augustine. And above all, and nearest to us in this Church, our own holy Patron and Father, St. Philip, occupies, with his Novena and Octave, fifteen out of the whole thirty-one days of the month. These are some of the choicest fruits of God's manifold grace, and they form the court of their glorious Queen.
Ven John Henry Newman
Observant (and nerdish) readers will note changes in the liturgical calendar between Newman's time and our own.