BARDAISAN (or Bardesanes) of Edessa (154–222 CE) was a philosopher, an ethnographer, and the first Syriac Christian theologian, later regarded as unorthodox.

Only a few events are known about the life of Bardaisan (Bar Dayṣān, or "son of [the local river] Dayṣān"). He attended the court of the king of Edessa, Abgar VIII (176–211), and probably fled from Edessa to Armenia after Abgar IX was taken prisoner by the Romans in 216. Bardaisan had a son who introduced metrical hymns in Syriac, which were imitated by later Syriac poets. Edessene Christianity of his time did not have a hierarchical structure, but was divided into various groups, such as the Jewish-Christians, the "orthodox" Christian minority, the Gnostics, and the Marcionites, who later came into conflict with Bardaisan and his school.

What can be ascribed to Bardaisan shows his familiarity with both Greek philosophy (Platonism, Stoicism) and Hellenistic astrological and ethnographic...