We know virtually nothing about Diadochus, except that he was bishop of Photicē in Epirus in the middle of the fifth century. He is mentioned by Photius as among the opponents of the monophysites contemporary with the Council of Chalcedon. The writings of his that survive are a Century of Gnostic Chapters on the spiritual life, a sermon on the Ascension, and a work called the Vision of St Diodochus, which takes the form of a series of questions and answers. His Century of Gnostic Chapters was very influential in the Greek East: it is quoted by, among others, Maximus the Confessor and appears in the Philocalia of Nicodemus of the Holy Mountain. It was also translated into Latin.
According to Olivier Clément, 'H.I. Marrou advances the hypothesis that he had been carried off in a Vandal raid on Epirus (Procopius mentions the raid) and taken captive to Carthage. This would account for the fact that the influence of this initiator of Byzantine tradition is found in the treatise On the Contemplative Life by Julian of Pomerium who live in Africa before becoming the teacher of Caesarius of Arles' (p. 323).
All eleven manuscripts of a work titled 'The Vision'—ὅρασις—attribute the work to [St] Diadochus. It is a dialogue of a dream, a dream in which the author converses with St John the Baptist. The topics about which they converse—in question and answer form—are ascetical topics: the essence of contemplation, the nature of Divine appearances, and the nature of the beatific vision. Much is reminiscent of [St] Dionysius the Areopagite, especially the section which deals with angelology. The ‘vision’ in glory of God is beautifully described: ‘Those who are to be jduged worthy of it are constantly in the light, always rejoicing, in glory, in the love of God, but incapable of conceiving wherein consists the nature of the light of God that enlightens them. In the same way, indeed, as God limits himself as he wills while remaining unlimited, so also he allows himself to be seen by remaining invisible. And what are we to understand by the virtue of God? A beauty without form that is known only in glory.’ There is the constant thought that, although we can only fully grasp the heavenly vision after the transfiguration of the body, it is yet reflected on the body when we approach the vision here on earth in ‘gnosis’. ‘The very energy of our spiritual gnosis teaches us that there is one natural sense of the soul, later divided into two energiess in consequence of Adam’s disobedience. But another sense is simple—that which comes to us from the Holy Spirit, which no one can know except those who willingly detach themselves from the advantages of this life in the hope of future blessings, those who by continence scourge the appetite of the corporeal senses. Only in these does the mind move with complete vigor thanks to its detachment, and can sense the Divine goodness in an indescribable way, following which it then communicates its own joy to its very body, according to the degree of its progress, exulting ceaselessly in its confession full of love: “In him”, says the Psalm, “my heart has haped, and my flesh has flourished again, and with all my will I shall confess him”. For the joy that then comes to the soul and body is an infallible reminder of the incorruptible life.’
A lot of Protestants and Catholics seem to have encountered St Diadochus through a book on desert spirituality by the Catholic priest, Henri Nouwen, called The Way of the Heart. There, Nouwen quotes from the 'Gnostic Chapters':
70. When the door of the steam baths is continually left open, the heat inside rapidly escapes through it; likewise the soul, in its desire to say many things, dissipates its remembrance of God through the door of speech, even though everything it says may be good. Thereafter the intellect, though lacking appropriate ideas, pours out a welter of confusing thoughts to anyone it meets, as it no longer has the Holy Spirit to keep its understanding free from fantasy. Ideas of value always shun verbosity, being foreign to confusion and fantasy. Timely silence, then, is precious, for it is nothing less than the mother of the wisest thoughts. (Philokalia I, p. 276)
Without having read Nouwen’s book, it is nevertheless interesting to reflect that while he himself may have the right sort of approach to learning from the Fathers, in the circles where he is read it strikes me that Masters of the Christian life like St Diadochus become just another offering on the smorgasboard of ‘spirituality’ (I write this after a brief look at a blog or two that have referenced this book, and the quote from St Diadochus in particular). Such readers take what they like from the Fathers but leave the rest, particularly if it disagrees with their peculiarly modern sensibilities and idiosyncratic views on Christianity and the spiritual life.
The blogger at Orthodox Monk has produced a fresh translation of the 'Gnostic Chapters' beginning here, while the Memory of Death blog has a convenient list of the relevant posts with samples of the translation here. There are some good quotes from St Diadochus here, here, and especially here. I shall give one of my own favourite passages below:
89. . . . When the intellect begins to perceive the Holy Spirit with full conciousness, we should realize that grace is beginning to paint the divine likeness over the divine image in us. Artists first draw the outline of a man in monochrome, and then add one colour after another, until little by little they capture the likeness of the subject down to the smallest details. In the same way the grace of God starts by remaking the divine image in man into what it was when he was first created. But when it sees us longing with all our heart for the beauty of the divine likeness and humbly standing naked in its atelier, then by making one virtue after another come into flower and exalting the beauty of the soul ‘from glory to glory’ (2 Cor. 3:18), it depicts the divine likeness on the soul. Our power of perception shows us that we are being formed into the divine likeness; but the perfecting of this likeness we shall know only by the light of grace. For through its power of perception the intellect regains all the virtues, other than spiritual love, as it advances according to a measure and rhythm which cannot be expressed; but no one can acquire spiritual love unless he experiences fully and clearly the illumination of the Holy Spirit. If the intellect does not receive the perfection of the divine likeness through such illumination, although it may have almost every other virtue, it will still have no share in perfect love. Only when it has been made like God—in so far, of course, as this is possible—does it bear the likeness of divine love as well. In portraiture, when the full range of colours is added to the outline, the painter captures the likeness of the subject, even down to the smile. Something similar happens to those who are being repainted by God’s grace in the divine likeness: when the luminosity of love is added, then it is evident that the image has been fully transformed into the beauty of the likeness. Love alone among the virtues can confer dispassion on the soul, for ‘love is the fulfilling of the law’ (Rom. 13:10). In this way our inner man is renewed day by day through the experience of love, and in the perfection of love it finds its own fulfillment. (Philokalia I, p. 288)
HT to the cool, but sadly no longer active Stephanos of Nikopolis for the line drawing of St Diadochus. The title of this post is taken from the Greek Troparion for St Diadochus shown at the bottom of the image.