Muratori, that most excellent master of textual criticism, relying on the testimony of a single Ambrosian manuscript, asserted that this sermon, rescued from obscurity, belonged to Saint Maximus, and published it together with others by the same author. This same sermon is found inscribed in the Turin codex as: On the Pasch, Sermon XIII. The foremost of the prophets, the most blessed Isaiah, who proclaimed aloud the mysteries of the Lord's nativity and resurrection, says among other things: 'Rejoice, O heaven, and let the earth exult; let the mountains break forth into gladness, and the hills into justice, for God has had mercy upon his people, and has comforted the lowly of his people' (Psalm 95).
This proclamation, brethren, pertains most especially to these days and foretells the paschal festivity, as we perceive both from the very sequence of the reading itself and as we are instructed by what follows. Rightly, therefore, are the heavenly things now summoned to all gladness, when the Only-begotten of the Most High, having shattered the gates of hell and cast down the devil, brought to most sorrowful mortals the joys of blessed eternity. And how could heaven not rejoice when it saw its Lord, the battle for our salvation accomplished, seated as victor upon the throne of his majesty and at the right hand of the Father? Heaven rejoices that its Lord, having fulfilled the purpose of the Father's will and by the merit of his triumph, has received the kingdom of the universe. 'Rejoice,' he says, 'O heaven, and let the earth exult.'
Surely the earth of the human race exults, which, sprinkled with the blood of the heavenly Lamb, is not only restored to paradise but is called to heaven to reign with the Lord. Let our flesh also exult, which is truly earth, since, glorified through Christ, it has merited fellowship with the Divinity. 'Let the mountains,' he says, 'break forth into gladness, and the hills into justice.' These mountains and hills that are roused to joys we may not unfittingly understand to be called the patriarchs, just as we read in the holy David: 'Thou dost enlighten wondrously from the everlasting mountains' (Psalm 75); and elsewhere: 'The mountains skipped like rams, and the hills like the lambs of the flock' (Psalm 113).
And not without reason are all the righteous called mountains and hills, who, forsaking the lowly things of an earthly manner of life, have raised the summit of their faith to the higher things of the heavenly life. Most justly, therefore, are the venerable patriarchs admonished by the prophetic word to take up gladness. For their offspring, that is, Christ the Lord, by the mystery of his death and resurrection, restored the lost life even to the fathers of the age gone by. The patriarchs rejoice in every way, from whose lineage was born the Son of God, who wiped clean the whole face of the world—long defiled by diabolical impieties—with the fresh blood of his own immaculate body.
And therefore, brethren, since we know that heaven rejoices, that earth exults, that the mountains and hills are glad, let us too offer to our God our religious joys; let us celebrate the Lord's Pasch, as the Apostle says: 'Not with the leaven of malice and wickedness, but with the unleavened bread of sincerity and chastity' (1 Corinthians 5). You will celebrate the Pasch, brother, with the unleavened bread of sincerity and chastity, if your senses, redolent of the Lord's bread, are formed with no leaven of vices, with no sprinkling of the devil. You will celebrate the Pasch and shine with the splendor of its brightness, if in your heart no darkness of adulterous thought obscures the light of so great a sacrament.
You will celebrate the Pasch with the unleavened bread of truth, if you come to the Church of God chaste, sober, just, peaceable, and full of brotherly charity. For no one can, with a life beyond correction and an impenitent heart, both hold fellowship with the devil in his crimes and celebrate the mystery of holiness with Christ. Let us therefore lay aside all the leaven of iniquity, that we may be able to be true partakers of this gladness—to which the mountains and hills are called together by the Holy Spirit through the prophetic voice, to which heaven also and earth are invited. For who is so numbed with dull sense?
Who is so blinded with a mind darkened, his eyes sunk into the earth, that he does not celebrate together, with all exultation, these vows of the whole world—in which shine forth the remission of sins, the grace of regeneration, the mystery of redemption, the glory of the resurrection, and the hope of eternity?