The Benedictine monks of the congregation of Saint Maur, in the appendix to the last volume of the works of Saint Ambrose, sermon 33, which is the 17th On the Fasts of Lent, say it is probable that this sermon is to be attributed to Maximus, whose both style and, in the Remigian codex, name too it presents for recognition. With the Remigian, which they praise, agrees the Turin codex, in which this heading is prefixed to the same sermon: Likewise on Lent, Sermon 13. It was perhaps delivered on Palm Sunday, as the same monks think they have gathered by conjecture. For on that day it was customary in most Churches for the Creed to be handed over to the candidates.
By the favour of the Godhead, behold, we have now almost completed the appointed fasts of Lent, and have fulfilled the precepts of Christ the Lord by the devotion of abstinence. It now remains that, just as his servants Moses and Elijah, by observing this most sacred number, deserved grace, so we too, by keeping this same time, may deserve it; and that there may be a like recompense in the reception of the reward for those whose labour is alike in the observance of the fast.
For Elijah, when heaven was closed by human iniquities, and no abundance of rains dripped down from above upon earthly things, and all things languished in the squalor of a long drought, and there was a great famine over the whole human race—since heaven gave no rain, nor did the earth bring forth its herbage—holy Elijah unlocked heaven by his fasts, and made the earth fruitful by his prayers (2 Kings 18). For he turned the drought of the one into rain, and dissolved the barrenness of the other into offspring; for so great a bounty of showers, at his prayers, watered the world, that dry things grew green again, dead things rose again, languishing things were healed.
And thus a certain channel of springs was poured into all things, so that, purification being made through the rain, the vices of all creatures were washed away, and by the benefit of that inundation the renewed appearance of the whole world arose again. Therefore let us too, observing the same fasts as Elijah, with prayers applied, unlock the closed heaven for our candidates; so that the shower of the saving laver may enlighten them. For heaven is closed to them, so long as the Holy Spirit, coming from heaven, does not yet quicken their hearts: they suffer, as it were, a drought, because they are not yet watered by the grace of baptism. They labour also in a great famine, since, as those who hunger, they desire the heavenly sacraments.
Let us therefore unlock heaven for them, that, the spiritual rain coming from above, their earth may be satisfied with the irrigation of the laver, and, the barrenness of offences being laid aside, they may begin to bring forth the fruits of virtues. For indeed the heavenly shower washes away the vices of sins, opens up the increases of justice, shakes off the dry dust of concupiscence, gladdens the useful purity of chastity, overwhelms the filthy dregs of avarice, nourishes the eternal bounty of mercy. For as, at the coming on of Elijah's rain, the earth produced every herbage; so also, at the coming on of Christ's laver, the soul brought forth every justice. And as there the fountains of rains watered the world, so that the now-mortified seeds of herbs might be quickened:
so also the fountain of baptism waters the human race, that it may quicken the mortified hearts of souls. This is the merit of those who observe these fasts: that by their prayers either the world may be renewed, or the brethren may be born anew. Heaven must therefore be unlocked for our candidates, since it is still closed to them; for heaven is closed to them, because they do not yet fully behold the mystery of the Trinity. For, heaven being closed to them, they know not what is done above heaven: nor can they know what is the substance of the Son and of the Father, unless first they shall have transcended the elements of the world.
For then will one be able to behold the divine mysteries of the Trinity, when he shall have the heavens opened by his own power, just as the blessed martyr Stephen unlocked the heavens for himself by his martyrdom, and saw the Saviour standing at the right hand, according to what he himself says: Behold, I see the heavens opened, and Jesus standing at the right hand of God (Acts 7). Therefore for him to whom the heavens are closed, it must be brought about that they be opened for him, so that above the heavens he may be able to behold Christ; for as long as they are closed to a man, he cannot see Christ reigning. But in what manner the closed heavens are to be opened, it behoves us to inquire. I think, however, that they cannot be opened otherwise, unless we take up the keys of Peter the apostle, which he received by the Lord's bestowal, as he himself said:
I will give you the keys of the kingdom of heaven (Matthew 16). Nay, let us ask Peter, that he himself, as a good doorkeeper of the heavenly palace, may open it for us. But what this key is, let us more diligently inquire. The key of Peter I would call the faith of Peter, by which he opened the heavens, penetrated the nether regions secure, and trod upon the seas undaunted. For so great is the power of apostolic faith, that all the elements lie open to it, that is, the angelic gates are not closed to it, the gates of Tartarus do not prevail, the currents of waters do not sink it down. But this very key, which we speak of, let us see of what it consists, and how it was made solid. I judge that it was forged by the working of twelve craftsmen;
for by the creed of the twelve apostles the holy faith was conceived, who, as skilled workers coming together into one, forged the key by their common counsel. For I would call the creed itself a certain key, by which the darkness of the devil is unlocked, that the light of Christ may come; the closed sins of the conscience are opened, that the manifest works of justice may shine forth. Therefore this key must be shown to our brethren, that they too, as disciples of Peter, may grow accustomed to unlock the nether regions for themselves and to open the heavens.