DIODORO. - Bishop of Tarsus, ascetic, and second founder of the Antiochene exegetical school, born in the first quarter of the 4th century, died before 392. He studied at Athens (Facundus of Hermiane, Pro defensione trium capit., 4, 2: PL 67, 621 B, 11-14), acquiring a broad secular culture; thus the observation of St. Jerome, who attributes to him «ignorantiam saecularium litterarum» (De vir. illustr., 119: PL 23, 750), is inaccurate. He was also a disciple of Silvanus, bishop of Tarsus, and of Eusebius of Emesa.
After completing his education, D. devoted himself to asceticism in an ascetic community near Antioch: there he applied himself to the study of Holy Scripture and became, together with his companion Carterius, superior of a group of ascetics that included St. John Chrysostom and Theodore of Mopsuestia.
Under the Arian emperors Constantius (337-61) and Valens (364-78), D. and his friend Flavian, not yet priests, carried on tireless activity in defense of the Nicene faith. When Leontius, the Arian bishop of Antioch (cf. Theodoret, Hist. eccl., 2, 19: PG 82, 1060), admitted the Arian Aetius among the deacons, Flavian and D. protested, and Leontius yielded. At that same time he taught the people to sing psalms and hymns antiphonally at the gatherings of the orthodox outside the Arian churches. This singing was so successful that Leontius himself requested that these meetings be held in the churches (Theodoret, ibid.); Semitic sources report that D. had learned this custom during his journey to Persia.
In 361 an orthodox bishop, St. Meletius, having become bishop of Antioch, ordained the two friends priests. When Julian the Apostate passed through Antioch the following year, D. was a priest and known to the emperor as the leader of the Christians. About 372 he went to Armenia, where his bishop Meletius was living in exile; there he also found St. Basil, with whom he formed bonds of friendship, as is evident from the Basilian correspondence (Epist., 135 and 244, 3: PG 33, 572 and 916). At the death of Valens (378), he was consecrated bishop of Tarsus in Cilicia. He took part in the Council of Antioch in the following year and in that of Constantinople in 381 (Theodoret, Hist. eccl., 5, 4: PG 82, 1204 A). In a decree of 30 July 381, Theodosius proclaimed Pelagius of Laodicea and D. of Tarsus models of orthodox faith for the diocese of the East (Hefele-Leclercq, II, 41). From the notice by St. Jerome of the year 392 (De vir. ill., 119), it appears that D. was already dead.
Of the numerous writings of D. (the Suda has handed down a list: PG 33, 1553), a large part has been lost. D. commented on almost all the books of the Old and New Testaments. There remains a treatise on hermeneutics with the suggestive title: What is the difference between theory and allegory? The polemical-dogmatic treatises were for the most part directed against the errors of Jews, pagans, Arians, and other heretics. In addition to the works listed by the Suda, Photius makes known to us a book against the Manichaeans and one on the Holy Spirit (Photius, Bibl., cod. 85, 102: PG 103, 288B, 372); St. Jerome knew a commentary on the letters of St. Paul; and Leontius of Byzantium knew a work Contra synousiastas, by which name he meant the Apollinarians. For the Syriac lists V. the article by R. Abramovski, Untersuchungen zu D. von Tarsus, in Zeitschr. f. Neutest. Wissensch., 30 (1931), p. 245 ff.
The fragments that have come down to us are found either in exegetical catenae or in polemical florilegia, whence the difficulty of establishing their authenticity and of understanding the author’s thought through passages removed from their context.
Migne collected certain fragments on the Octateuch and the Psalms (PG 33, 1561-1628), subsequently enlarged in Deconinck’s edition (further supplemented by R. Devreese, in Rev. bibl., 45 [1936], pp. 217-20). Mariès’s hypothesis of attributing to D. the complete commentary on the Psalms by Anastasius of Nicaea has not been confirmed. The passages on the Epistle to the Romans were edited by Staab.
There remain the few dogmatic-polemical passages. Those collected in PG 33, 1560 ff. are taken either from Leontius of Byzantium (Contra Nestorianos et Eunomianos, III, 43: PG 86, 1, 1385 ff.) or from Cyril of Alexandria (fragments of the work Contra Diodorum et Theodorum: PG 76, 1437 ff.; some in Mansi, IX, 215 b, 219 b c, 231: Council of Constantinople, III, 553). Other fragments exist in the Palatine Collection of the Council of Ephesus (E. Schwartz, Acta conc. oec., I, 5, pp. 177-79, prior to the year 550); Syriac ones are in M. Brière, Fragments syriaques de D. d. T. réédités et traduits, in Revue de l'Orient chrétien, 3rd series, 10 (1946), pp. 231-85. Abramovski studied the transmission of these fragments in the manuscripts (ibid., pp. 247-53), without addressing the problem of their authenticity. M. Richard (Les traités de Cyrille d'Alexandrie...), studying the aforesaid fragments, reaches the following conclusions: D. wrote a work Contra synousiastas (that is, against the Apollinarians) in two books. St. Cyril polemicizes against the first book in his Contra Diodorum. Six fragments of this first Diodoran book have been transmitted in the Palatine Collection (the fourth fragment, homo ungitur Iesus, is by Paul of Samosata); seven or more others may be found in the Philalethes and the Contra impium grammaticum of Severus of Antioch. St. Cyril likewise polemicized against the second Diodoran book, attributing it to Theodore. When Cyril wrote, he had before him not the actual works of D. and Theodore, but florilegia compiled by the Apollinarians (and therefore probably also falsified). In this compilation, offered to him at Jerusalem in 438, Cyril would already have found the confusion between D. and Theodore, which, writing hastily, he failed to notice.
There also remains Photius’s lengthy analysis (Bibliot., 223: PG 103, 829-77) of the fragments of the Contra fatum, which have been studied by V. Ermoni (Diodore de Tarse et son rôle doctrinale, in Le Muséon, 2 [1901], pp. 424-44) and by P. Doll (Κατὰ εὐμερίενης, Bonn 1923).
For a stylistic judgment on D., in view of the absence of complete works, one must be content with the criticism of Photius (Bibliot., 223: PG 103, 820 and 877) and of St. Basil (ep. 135: PG 33, 572).
Given the uncertainty of the sources, D.’s doctrine cannot be set forth. On the basis, however, of the sound Antiochene doctrine in the introduction to the Psalms published by L. Mariès, the following may be noted. The author is concerned for the understanding of the Psalms sung by the brethren (p. 82, lines 12 ff., 24 ff., and p. 86, 9 ff.); he combats two opposite excesses: Jewish literalism and allegorism of pagan origin; he wishes to follow the middle way of «theory» (p. 88, 22 ff.), that is, the understanding of the prophetic sense concerning Christ, while always presupposing the historical sense (92, 4 ff. and 88, 3 ff.). When he speaks of allegory, he sometimes refers to Christians who, through their allegorism, do violence to the meaning of Holy Scripture (p. 88, 11), and sometimes also to pagans, who hold that allegory (p. 90, 6 ff.) completely eliminates the historical sense. This attention to the historical sense does not prevent Holy Scripture from being a reality adaptable to the needs of many, by reason of the Grace of Him who works within (p. 96, 5 ff., and especially 98, 19 ff.). Cf. A. Vaccari, La « teoria » esegetica antiochena, in Biblica, 1 (1920), pp. 12, 13, on Antiochene theory; and, on the relation between the exegesis of the Antiochene and Alexandrian schools, cf. also H. de Lubac, Typologie et allégorisme, in Recherches de science, religieuse, 34 (1947), pp. 180-226.
Per la dottrina dommatica e specialmente cristologica di D. bisogna notare l'influenza aristotelica non solo in certi punti della dottrina fisica ma anche nel modo di ragionare (cf. Ermoni, op. cit., p. 433 sg. ed Abramowski, op. cit., p. 254). Secondo un frammento siriano, citato da Abramowski (ibid.), D. avrebbe messa la ragione accanto alla Bibbia come fonte della teologia. Scrivendo contro Apollinare di Laodicea, D. insegnò invece l'umanità perfetta e la divinità di Cristo, separando le nozioni divine dalle umane, separando il Figlio di Dio dal Figlio di David, Iddio Verbo dall'uomo Gesù Cristo. Il Figlio di Dio non è figlio di David ma piuttosto il di lui Signore (PG 33, 1560C). L'unione dei due figli è spiegata come un'abitazione del Dio Verbo nel suo tempio Gesù (PG 33, 1560AB) o sotto l'immagine del vestito. Il Verbo si sarebbe vestito dell'umanità di Gesù (Schwartz, op. cit., p. 179, lin. 4). Bisogna tuttavia ricordare che queste constatazioni sono basate esclusivamente su frammenti scelti dopo la morte di D. nella lotta antinestoriana per mostrare che l'errore di Nestorio aveva già i suoi precedenti. S. Giovanni Crisostomo, il suo grande discepolo, non ci ha lasciato nemmeno un accenno sulla dottrina del suo maestro.
M. Richard, Les traités de Cyrille d'Alexandrie contre Diodore et Théodore et les fragments dogmatiques de Diodore de Tars (Mélanges dédiés à la mémoire de Félix Grat), I, Parigi 1946, pp. 99-116; G. Mercati, Osservazioni ai proami del Salterio di Orgeno, Ippolito, Eusebio, Cirillo (Studi e testi, 142), Città del Vaticano 1948. - Per i 4 trattati pseudo-giustini attribuiti a torto a D. da Harnack e da Fetissof, V. BARDENHEWER, OTTO, III, p. 310 sg. - Policarpo Sherwood