This homily, in which Peter's compunction is clearly proved, I judge is not to be ascribed to St Ambrose, as is read in two codices — Vatican 1277, page 62, and the Orvieto one — and in some editions; but rather to the holy bishop of Turin, Maximus. This can be gathered from its connection with the preceding one, from the similar manner of writing, from the heaping-up of antitheses which is proper to Maximus, and from the number of codices in which his name is inscribed. These codices are five: St Gall homily 67, Santa Croce in Jerusalem 99, homily 50, the Turin one, the Laurentian X, Plut. XIV, page 288, and IV, Plut. XXXIII of the library formerly of Santa Croce of the Friars Minor, now in the Laurentian.
The above-praised Vatican codex 1277 has a title of this kind: 'A Sermon Proper for the Birthday of St Peter'; another Vatican, 6451: 'A Sermon on the Chains of St Peter.' Neither of them can fit: not the first, because the birthday of the saints is wont to be called the day of their passing to glory; not the second, since nothing about the feast of Peter's chains is read in this homily. The Turin codex has 'Likewise, and concerning the same St Peter'; the rest, 'What follows,' namely the same homily, which is 'On the Penitence of Peter.' Alcuin, page 536 of the Venice edition of 1537, placed the same under the name of Maximus among the sermons for the feast of Sts Peter and Paul. But Gymnicus, page 136, Galesinius, page 128, Raynaudus, page 216, Curndius, tome II, page ...
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1237, etMargarinusinBibl. Max. tom. VI, pag. 24, designatotitulo: DeeodemPetroapostolo, S. Maximoascripserunt. Nosettitulum, etidemhomiliæprincipiumservamus (quodaliiprolibitomutavere) utinMaurinaappendiceserm. S. Augustininum. 192, pag. 226, edit. Antuerp. an. 1700, etincodiceVaticano 6451, legimus. Astroximusasuperioredominica, S. PetruminSalvatorispassionesuiserroribusprofecisse, etposteaquamnegavitDominumbDeum, fuissemelioremFideliorenimfactusest, postquamfidemseperdidissedeOevit; atqueideomajoremgratiamreperitquamamisit; tanquambonusenimpastortuendumgregemaccepit, utquisibianteinfirmusfuerat, fiereteomnibusfirmamentum;
... page 1237, and Margarinus in the Bibliotheca Maxima, tome VI, page 24, under the assigned title 'Concerning the Same Apostle Peter,' ascribed it to St Maximus. We preserve both the title and the same opening of the homily (which others have changed at their pleasure), as we read in the Maurist appendix to the sermons of St Augustine, no. 192, page 226, of the Antwerp edition of the year 1700, and in the Vatican codex 6451. We showed from last Sunday that St Peter profited by his own errors in the Saviour's passion, and that after he denied the Lord and God he became better. For he was made more faithful after he wept that he had lost his faith; and therefore he found greater grace than he had lost; for as a good shepherd he received the flock to be guarded, so that he who before had been weak for himself might become a support for all;
and he who himself had wavered under the trial of the questioning might ground the rest in the stability of faith. In short, for the solidity of his devotion he is called the rock of the Churches, as the Lord says: 'Thou art Peter, and upon this rock I will build my Church' (Matthew 16). For he is called a rock because he first laid among the nations the foundations of faith, and like an immovable stone holds together the framework and mass of the whole Christian work. But Peter is called 'rock' for his devotion, and the Lord is named 'rock' for his power, as the Apostle says: 'And they drank of the spiritual rock that followed them; and that rock was Christ' (1 Corinthians 10). Rightly he earns fellowship in the name who earns fellowship also in the work;
for in the same house Peter laid the foundation, Peter plants, the Lord gives the increase, the Lord supplies the watering (cf. 1 Corinthians 3). For Peter profits by his temptations, rejoices in his weepings, grows by his perils. For so upon the sea, while the daring wayfarer steps upon the waves, he wavers in his going, but grows strong in affection; he is endangered in body, but slips not in devotion; he sinks with his feet, but is upheld by Christ's right hand; faith upholds him whom the wave was sinking; and him whom the storm of the billows was troubling, the Saviour's love was strengthening. For Peter walked upon the sea by love rather than by his feet; for he saw not where he should set the print of his foot, but he saw where he should fix the footstep of charity.
For, set upon the sea, he beholds the Lord, and led by love of him he goes down into the sea; he thinks not of the failing waters, nor of the running streams; and while he looks to Christ, he looks not at the element. He believes that even amid the waves he will find a solid footing by faith: though the sea be tossed by billows, the deep by winds, Peter's path which leads to the Lord is nevertheless not troubled. Peter therefore walks upon the waters, and beneath his feet the soft wave does not yield. We read in the Old Testament (Exodus 14) that the sons of Israel walked through the Red Sea by dry ways, and that, for the safety of those going, the wave, lest it should slip, was changed into a certain solidity.
How much better is this, where, as Peter walks, the wave is neither changed nor slips, the water is neither made solid nor recoils. Better, I say, it is, where the same wave both surges and upholds, where the same flood both engulfs and serves. There, that the people of Israel might be borne through the sea, nature had lost its own course; here Peter is borne upon the waters, and the streams lose not their own course. The daring wayfarer therefore, the apostle, takes the road of a new journey: now he ascends the mass of the curved flood, now he descends the wave of the subsiding hollow, and amid the sea-billows the ascent and descent of his journey is not lacking to him. But when, troubled by winds, tossed by storms, he begins to fear what he had believed, at once the flood is drawn away from him, the wave is withdrawn;
and soon, as his faith flags, his path gives way; then, crying out, he beseeches the Lord Jesus that he be saved; and the Saviour, taking him by the hand, frees him and rebukes him, saying, 'O thou of little faith, wherefore didst thou doubt?' That is: Why art thou of so little faith, that thou who by believing hadst begun to walk on the sea didst not by persevering pass over it? For it is written: 'He that shall persevere unto the end, he shall be saved' (Matthew 10). But while thou delayest and doubtest, thou hast lost the way thou hadst entered upon. Why, I say, art thou of so little faith, that thou dost not, by the same faith with which thou hadst begun to come, arrive? Understand therefore that on the sea faith bore thee, faithlessness sank thee.
Therefore, brethren, holy Peter, while he tosses, while he sinks, while he is in peril, so comes to the Lord; he shows us that one hastens to Christ only through perils; for there are many diabolical waves in this world, many shipwrecks of temptations, from which we can be freed thus, if the Saviour stretches out his hand to us as we cry. Let us therefore not cease to cry to the Lord: he will not deny his accustomed help ... [and gave him] solidity, namely an inward and stable love toward the Lord, by which he merited to be established as the rock of the Church, or the foundation of the new spiritual building, and to rejoice in the likeness and property of the name of Christ himself.
Thirdly he teaches that Peter first laid among the nations the foundations of faith, and that upon him, as upon an immovable stone, the whole Christian work is raised and sustained. Fourthly he asserts that what Peter plants in the Church — that is, in the teaching of the doctrine of the divine word — is watered by heavenly irrigations, grows, and comes to maturity. By these things, therefore, the supreme power of Peter, his pre-eminence, the truth of his doctrine, and the universal governance of the mystical body, committed by Christ to Peter, are proved.