St Peter Damian, who was essentially a man of prayer, meditation and contemplation, was also a fine theologian: his reflection on various doctrinal themes led him to important conclusions for life. Thus, for example, he expresses with clarity and liveliness the Trinitarian doctrine, already using, under the guidance of biblical and patristic texts, the three fundamental terms which were subsequently to become crucial also for the philosophy of the West: processio, relatio and persona (cf. Opusc. XXXVIII: PL CXLV, 633-642; and Opusc. II and III: ibid., 41 ff. and 58 ff). However, because theological analysis of the mystery led him to contemplate the intimate life of God and the dialogue of ineffable love between the three divine Persons, he drew ascetic conclusions from them for community life and even for relations between Latin and Greek Christians, divided on this topic. His meditation on the figure of Christ is significantly reflected in practical life, since the whole of Scripture is centred on him. The “Jews”, St Peter Damian notes, “through the pages of Sacred Scripture, bore Christ on their shoulders as it were” (Sermo XLVI, 15). Therefore Christ, he adds, must be the centre of the monk’s life: “May Christ be heard in our language, may Christ be seen in our life, may he be perceived in our hearts” (Sermo VIII, 5). Intimate union with Christ engages not only monks but all the baptized. Here we find a strong appeal for us too not to let ourselves be totally absorbed by the activities, problems and preoccupations of every day, forgetting that Jesus must truly be the centre of our life.

Communion with Christ creates among Christians a unity of love. In Letter 28, which is a brilliant ecclesiological treatise, Peter Damian develops a profound theology of the Church as communion. “Christ’s Church”, he writes, is united by the bond of charity to the point that just as she has many members so is she, mystically, entirely contained in a single member; in such a way that the whole universal Church is rightly called the one Bride of Christ in the singular, and each chosen soul, through the sacramental mystery, is considered fully Church”. This is important: not only that the whole universal Church should be united, but that the Church should be present in her totality in each one of us. Thus the service of the individual becomes “an expression of universality” (Ep 28, 9-23). However, the ideal image of “Holy Church” illustrated by Peter Damian does not correspond as he knew well to the reality of his time. For this reason he did not fear to denounce the state of corruption that existed in the monasteries and among the clergy, because, above all, of the practice of the conferral by the lay authorities of ecclesiastical offices; various Bishops and Abbots were behaving as the rulers of their subjects rather than as pastors of souls. Their moral life frequently left much to be desired. For this reason, in 1057 Peter Damian left his monastery with great reluctance and sorrow and accepted, if unwillingly, his appointment as Cardinal Bishop of Ostia. So it was that he entered fully into collaboration with the Popes in the difficult task of Church reform. He saw that to make his own contribution of helping in the work of the Church’s renewal contemplation did not suffice. He thus relinquished the beauty of the hermitage and courageously undertook numerous journeys and missions.

Because of his love for monastic life, 10 years later, in 1067, he obtained permission to return to Fonte Avellana and resigned from the Diocese of Ostia. However, the tranquillity he had longed for did not last long: two years later, he was sent to Frankfurt in an endeavour to prevent the divorce of Henry iv from his wife Bertha. And again, two years later, in 1071, he went to Monte Cassino for the consecration of the abbey church and at the beginning of 1072, to Ravenna, to re-establish peace with the local Archbishop who had supported the antipope bringing interdiction upon the city.
On the journey home to his hermitage, an unexpected illness obliged him to stop at the Benedictine Monastery of Santa Maria Vecchia Fuori Porta in Faenza, where he died in the night between 22 and 23 February 1072.