Suidas (Souidas, Soudas), author of, perhaps, the most important Greek lexicon or encyclopedia. Nothing is known of Suidas himself except that he lived about the middle of the tenth century, apparently at Constantinople, and that he was probably an ecclesiastical person devoted to literary studies. But his lexicon is one of the most valuable documents of Greek philology, grammar, and literary history. He uses material from the classical period down to his own time; a long chain of later authors, from Eustathius of Thessalonica (c. 1192), quote from him. Suidas’s lexicon is something between a grammatical dictionary and an encyclopedia in the modern sense. He explains the source, derivation, and meaning of words according to the philology of his period, using such earlier authorities as Harpokration and Helladios. There is nothing specially important about this part of his work. It is the articles on literary history that are valuable. In these he gives a supply of details, and to some extent quotations, from authors whose works are otherwise lost. He uses older scholia to the classics (Homer, Thucydides, Sophocles, etc.), and for later writers, Polybius, Josephus, the “Chronicon Paschale“, George Syncellus, George Hamartolus, and so on.
So his lexicon represents a convenient work of reference for persons who played a part in political, ecclesiastical, and literary history in the East down to the tenth century. His chief source for this is the encyclopedia of Constantine VII Porphyrogenitus (912-59), and for Roman history the excerpts of John of Antioch (seventh century). Krumbacher (op. cit., 566) counts two main sources of his work: Constantine VII for ancient history, Hamartolus (Georgios Monarchos) for the Byzantine age. The lexicon is arranged, not quite alphabetically, but according to a system (formerly common in many languages) called antistoichia; namely the letters follow phonetically, in order of sound (of course in the pronunciation of Suidas’s time, which is the same as modern Greek). So for instance ai comes after e; ei, ?i come together after z, o after o, and so on. The system is not difficult to learn and remember, but in some modern editions (Bekker) the work is rearranged alphabetically. Suidas contains much material for church history among his biographical articles. But there is very little of this kind that is not also known from other sources. His lexicon still may fulfil its original purpose as a convenient work of reference.