He was born around 400 in Bethelia, a small town near Gaza, into a wealthy Christian family of Palestine.
What he has to tell us of the history of Southern Palestine was derived from oral tradition. He appears familiar with the region around Gaza, and mentions having seen Bishop Zeno of Majuma, the seaport of Gaza.
Sozomen wrote that his grandfather lived at Bethelia, near Gaza, and became a Christian together with his household, probably under Constantius II. A neighbor named Alaphrion was miraculously healed by Saint Hilarion who cast out a demon from Alaphrion, and, as eyewitnesses to the miracle, his family converted, along with Alaphrion's. The conversion marked a turning-point in the Christianization of southern Palestine, according to his account.
The grandfather became within his own circle a highly esteemed interpreter of Scripture. The descendants of the wealthy Alaphrion founded churches and convents in the district, and were particularly active in promoting monasticism. Sozomen himself had conversed with one of these, a very old man. He tells us that he was brought up under monkish influences and his history bears him out.
Sozomen seems to have been brought up in the circle of Alaphrion and acknowledges a debt of gratitude to the monastic order. His early education was directed by the monks in his native place. It is impossible to ascertain what curriculum he followed in these monastic schools, but his writings give clear evidence of the thoroughness with which he was grounded in Greek studies.
As a man he retained the impressions of his youth, and his great work later was to be also a monument of his reverence for the monks in general and for the disciples of Hilarion in particular.
As an adult he acquired training as a lawyer. He studied law in Beirut. He then went to Constantinople to start his career as a lawyer, perhaps at the court of Theodosius II. While thus engaged he conceived, around the year 443 the project of writing a history of the Church.
Sozomen wrote two works on church history, of which only the second one is extant.
His first work covered the history of the Church, from the Ascension of Jesus to the defeat of Licinius in 323, in twelve books. His sources for it included Eusebius of Caesarea, the Clementine homilies, Hegesippus, and Sextus Julius Africanus.
Sozomen's second work continues approximately where his first work left off. He wrote it in Constantinople, around the years 440 to 443 and dedicated it to Emperor Theodosius II.
The work is structured into nine books, roughly arranged along the reigns of Roman Emperors:Book I: from the conversion of Constantine I until the Council of Nicea (312–325)
Book II: from the Council of Nicea to Constantine's death (325–337)
Book III: from the death of Constantine I to the death of Constans I (337–350)
Book IV: from the death of Constans I to the death of Constantius II (350–361)
Book V: from the death of Constantius II to the death of Julian the Apostate (361–363)
Book VI: from the death of Julian to the death of Valens (363–375)
Book VII: from the death of Valens to the death of Theodosius I (375–395)
Book VIII: from the death of Theodosius I to the death of Arcadius (375–408).
Book IX: from the death of Arcadius to the accession of Valentinian III (408–25).
Book IX is incomplete. In his dedication of the work, he states that he intended cover up to the 17th consulate of Theodosius II, that is, to 439. The extant history ends about 425. Scholars disagree on why the end is missing. Albert Guldenpenning supposed that Sozomen himself suppressed the end of his work because in it he mentioned the Empress Aelia Eudocia, who later fell into disgrace through her supposed adultery. However, it appears that Nicephorus, Theophanes, and Theodorus Lector did read the end of Sozomen's work, according to their own histories later. Therefore, most scholars believe that the work did actually come down to that year, and that consequently it has reached us only in a damaged condition.
Sozomen borrowed heavily from other sources for his work.
The source for about three-fourths of his material was the writings of Socrates Scholasticus. The literary relationship of these writers appears everywhere. Valesius asserted that Sozomen read Socrates, and Robert Hussey and Guldenpenning have proved this. For example, Socrates, in I.x, relates an anecdote which he had heard, and says that neither Eusebius nor any other author reports it, yet this anecdote is found in Sozomen, I.xxii, the similarity of diction showing that the text of Socrates was the source.
The extent of this dependence cannot be accurately determined. Sozomen used the work of Socrates as a guide to sources and order. In some matters, such as in regard to the Novatians, Sozomen is entirely dependent on Socrates.
But Sozomen did not simply copy Socrates. He went back to the principal sources used by Socrates and other sources, often including more from them than Socrates did.
He used the writings of Eusebius, the first major Church historian. The Vita Constantini of Eusebius is expressly cited in the description of the vision of Constantine.
Sozomen appears also to have consulted the Historia Athanasii and also the works of Athanasius including the Vita Antonii. He completes the statements of Socrates from the Apologia contra Arianos, lix, sqq., and copies Athanasius' Adv. episcopos AEgypti, xviii-xix.
Rufinus is frequently used. Instructive in this respect is a comparison of Sozomen, Socrates, and Rufinus on the childhood of Athanasius. Rufinus is the original; Socrates expressly states that he follows Rufinus, while Sozomen knows Socrates' version, but is not satisfied with it and follows Rufinus more closely.
The ecclesiastical records used by Sozomen are principally taken from Sabinus, to whom he continually refers. In this way he uses records of the synods from that of Tyre (335) to that of Antioch in Caria (367).
For the period from Theodosius I, Sozomen stopped following the work of Socrates and followed Olympiodorus of Thebes, who was probably Sozomen's only secular source. A comparison with Zosimus, who also made use of Olympiodorus, seems to show that the whole ninth book of Sozomen, is mostly an abridged extract from Olympiodorus.
Sozomen used many other authorities. These include sources relating to Christianity in Persia, monkish histories, the Vita Martini of Sulpicius Severus, the works of Hilarius, logoi of Eustathius of Antioch, the letter of Cyril of Jerusalem to Constantius concerning the miraculous vision of the cross, and Palladius.
He also used oral tradition, adding some of the most distinctive value to his work.
The work of Sozomen is interesting and valuable for many reasons. In the first place he pays more attention than any of the older historians to the missionary activity of the Christians, and to him we are indebted for much precious information about the introduction of Christianity among the Armenians, the Saracens, the Goths, and other peoples. The history is especially rich in information regarding the rise and spread of monasticism, and the labours of the early founders of monasteries and monastic communities.
The history as a whole is fairly comprehensive, and though his treatment of affairs in the Western Church is not full, his pages abound in facts not available elsewhere and in documentary references of the highest importance. The spirit and interest of Sozomen's history is clearly apparent; he follows the thread of the narrative of Socrates but seeks to improve upon and to excel his original by elegance of diction, and by the use of excellent sources of which he makes skilful use.
Sozomen made a painstaking effort to be acquainted with all the sources of information on the subjects which he touched, and he had a passionate desire for the truth. Generally he follows his authorities closely, some times almost literally; when they differ, he occasionally gives the various versions.
The historical exposition is altogether impersonal; Sozomen assumes (III.xv) that the task of history is to assemble facts without adding anything to them, hence he indulges in little criticism and usually adopts the views of his sources. This he does to such an extent that he has been charged with Arianism and Novatianism. In reality, in accord with his legal training, he has no opinion in theological questions; at the same time he was thoroughly pious and a great admirer of monasticism.
In his attitude towards the Church, in his treatment of the Scriptures, and in his views of the hierarchy and ecclesiastical order and dignity, he is always animated by feelings of submission and respect. He was filled with a profound conviction of the Providential purpose of Christianity, and of its mission, under Divine guidance, for the regulation of the affairs of mankind.
In doctrinal matters he aimed constantly at being in thorough accord with the Imperial Roman Church party, and was a consistent opponent of heresy in all its forms. But, while he maintained a constant attitude of hostility to Arianism, Gnosticism, Montanism, Apollinarianism, etc., he never assailed the leaders of these heresies or allowed himself to indulge in bitter personal attacks. "Let it not be accounted strange", he says, "if I have bestowed commendations upon the leaders or enthusiasts of the above-mentioned heresies. I admire their eloquence and their impressiveness in discourse. I leave their doctrine to be judged by those whose right it is" (III.xv).
Because much of Sozomen's work follows Socrates, he has been criticized as attempting to compose a better church history than that of Socrates, but only being partially successful. He frequently offers additional material but rarely improves upon his prototype. Sozomen did not track chronological data as closely as Socrates.
There are many faults and shortcomings in his work. Of many of these he himself was conscious, but it was not in his power to correct them. Frequently it was hard for him to know the truth because of the mass of divergent evidence with which he had to deal, frequently there was not enough evidence, but in every case he aimed at expressing the truth and at making his work serve some useful purpose in the defence or elucidation of Christian ideas.
The work of Sozomen was first printed (editio princeps) by Robert Estienne at Paris in 1544, on the basis of Codex Regius, 1444. There are later editions by Christophorson and Ictrus (Cologne, 1612).
A noteworthy edition was done by Valesius (Cambridge, 1720), who used, besides the text of Stephens, a Codex Fucetianus (now at Paris, 1445), "Readings" of Savilius, and the indirect traditions of Theodorus Lector and of Cassiodorus-Epiphanius.
Hussey's posthumous edition (largely prepared for the press by John Barrow, who wrote the preface) is important, since in it the archetype of the Codex Regius, the Codex Baroccianus 142, is collated for the first time. But this manuscript was written by various hands and at various times and therefore is not equally authoritative in all its parts.
There is an excellent English translation by Chester David Hartranft, with a learned though somewhat diffuse introduction, in the Nicene and Post-Nicene Fathers, II (published New York, 1890). (This text is available on-line at the Christian Classics Ethereal Library.)