John the Lydian orJohn Lydus (Greek:Ἰωάννης Λαυρέντιος ὁ Λυδός;Latin:Ioannes Laurentius Lydus) (c. AD 490 –c. 565) was aByzantine administrator and writer. He is considered a key figure in antiquarian studies from the fourth to the sixth century A.D. Although he is a secondary author, his works are significant because they are filled with valuable insights into history, astronomy, astrology, mythology, religion, and language. Additionally, they provide important information on Roman and Byzantine culture, making them worthy of in-depth study.^[1]

He was born in AD 490 atPhiladelphia inLydia, whence hiscognomen "Lydus". At an early age he set out to seek his fortune inConstantinople, and held high court and state offices in thepraetorian prefecture of the East underAnastasius andJustinian. Around 543, Lydus was appointed to a chair of Latin language and literature at an institute of higher education of Constantinople. In 552, he lost Justinian's favour and was dismissed. The date of his death is not known, but he was probably alive during the early years ofJustin II (reigned 565–578).^[2]

During his retirement he occupied himself in the compilation of works on the antiquities of Rome, three of which have been preserved:

1. De Ostentis (Gr.Περὶ Διοσημείων), on the origin and progress of the art ofdivination
2. De Magistratibus reipublicae Romanae (Gr.Περὶ ἀρχῶν τῆς Ῥωμαίων πολιτείας), especially valuable for the administrative details of the time of Justinian; the work is now dated to 550 by Michael Maas.^[3]
3. De Mensibus (Gr.Περὶ τῶν μηνῶν), a history of the different pagan festivals of the year.

The chief value of these books consists in the fact that the author made use of the works (now lost) of old Roman writers on similar subjects. Lydus was also commissioned by Justinian to compose a panegyric on the emperor, and a history of hiscampaign againstSassanid Persia; but these, as well as some poetical compositions, are lost.^[2]

He was interested in gynaecology and embryology and included several related passages in his "De Mensibus", with references to previous authors. His sources are mainly Greek, and two of them are Latin.^[4]

There is an edition ofDe Ostentis byCurt Wachsmuth (1897), with full account of the authorities in theprolegomena.^[2]

There is an edition ofDe Magistratibus andDe Mensibus byRichard Wünsch (1898–1903).^[5] See also the essay byCB Hase (the first editor of theDe Ostentis) prefixed toI. Bekker's edition of Lydus (1837) in the BonnCorpus scriptorum hist. Byzantinae.^[2]

ForDe Magistratibus, Wünsch's edition has been superseded by Anastasius C. Bandy's 1983 edition and translation.

See also:

• The Works of Ioannis Lydus, Vols. I–IV (Edwin Mellen Press, 2013). New critical translations of De Mensibus, De Ostentis and De Magistratibus by Anastasius Bandy. Co-edited by Anastasia Bandy, Demetrios J. Constantelos and Craig J. N. de Paulo.
• John the Lydian,De Magistratibus. On the Magistracies of the Roman Constitution. Translated by T. F. Carney. December 1971,Coronado Press.
• John the Lydian,On powers, or, The magistracies of the Roman state / Ioannes Lydus; introduction, critical text, translation, commentary, and indices by Anastasius C. Bandy. Series: Memoirs of the American Philosophical Society, v. 149ISSN 0065-9738. Philadelphia : American Philosophical Society, 1983, c1982. Greek text, parallel English translation. Based on the Codex Caseolinus.
• Des magistratures de l'état romain. Jean le Lydien. Text, French translation and commentary by Michel Dubuisson, Jacques Schamp. Belles Lettres (2006)

•   This article incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Lydus, Joannes Laurentius".Encyclopædia Britannica. Vol. 17 (11th ed.). Cambridge University Press. p. 158.

• Corpus scriptorum historiae byzantinae (Bonn, 1837) edition of the works of John Lydus: Greek, with Latin translation at the bottom of each page.
• Joannes Lydus Laurentius Opera Omnia by Migne Patrologia Graeca: Greek, with analytical indexes
• Teubner edition ofDe Mensibus (1898) by R. Wünsch. (Greek text only)
• English translation ofDe Mensibus (with annotations and introduction) by Mischa Hooker, 2nd ed. (2017)
• English translation of selected portions ofDe Mensibus, Book IV: months February-July, September-December, by Mischa Hooker (1st ed.)