Every Catholic knows, dearly beloved, that today's feast is among the greatest of the year; none doubts how muck reverence is due to that day which the Holy Spirit sealed with the miracle of his gift. Today is the tenth day since the Lord ascended above all heavens to sit at the right hand of God the Father, and the fiftieth since his resurrection; and in it is contained a great mystery comprising God's saving acts both old and new. For as on the fiftieth day after the sacrifice of the passover lamb the law was given on Sinai to the Hebrews who had escaped from Egypt, so after the passion of Christ, in which the true Lamb of God was sacrificed, and fifty days from his resurrection, the Holy Spirit descended upon the apostles and the gathering of the faithful.