Marcellus Empiricus, also known as Marcellus Burdigalensis (“Marcellus of Bordeaux”), was a Latin medical writer from Gaul at the turn of the 4th and 5th centuries. His only extant work is the De medicamentis, a compendium of pharmacological preparations drawing on the work of multiple medical and scientific writers as well as on folk remedies and magic. It is a significant if quirky text in the history of European medical writing, an infrequent subject of monographs, but regularly mined as a source for magic charms, Celtic herbology and lore, and the linguistic study of Gaulish and Vulgar Latin. Bonus auctor est (“he’s a good authority”) was the judgment of J.J. Scaliger, while the science historian George Sarton called the De medicamentis an “extraordinary mixture of traditional knowledge, popular (Celtic) medicine, and rank superstition.” Marcellus is usually identified with the magister officiorum of that name who held office during the reign of Theodosius I. Life and political career Little is known of the life of Marcellus. The primary sources are: Marcellus’s own preface to the De medicamentis; the Codex Theodosianus (probably referring to this Marcellus); a letter written in 399 by Symmachus to a Marcellus who is likely to have been the medical writer; a letter written by the Antiochan scholar Libanius that mentions a Marcellus; an inscription in Narbonne (his association with which would require that he not be from Bordeaux; see below); an anecdote in Orosius about an unnamed Gaul (also a highly conjectural link). The Gallic origin of Marcellus is rarely disputed, and he is traditionally identified with the toponym Burdigalensis; that is, from Bordeaux (Latin Burdigala), within the Roman province of Aquitania. In his prefatory epistle, he refers to three Bordelaise praetorian prefects as his countrymen: Siburius, Eutropius, and Julius Ausonius, the father of the poet Decimus Magnus Ausonius. He is sometimes thought to have come from Narbonne rather than Bordeaux. There has been an attempt to make a Spanish senator of him on the basis of Symmachus's reference to property he owned in Spain; but this inference ignores that Marcellus is said explicitly to have left Spain to return to living in avitis penatibus, or among the household spirits of his grandfathers — that is, at home as distinguished from Spain. He probably wrote the De medicamentis liber during his retirement there. The author of the De medicamentis is most likely the Marcellus who was appointed