Polemius Silvius (fl. 5th century) was the author of an annotated Julian calendar that attempted to integrate the traditional Roman festival cycle with the new Christian holy days. His calendar, also referred to as a laterculus or fasti, dates to around 448–449. He was active in southeastern Gaul.
Polemius was among the Christian cultural elite working within the imperial bureaucracy in Gaul under Valentinian III. He was a friend of Hilarius of Arles. The Gallic Chronicle of 452, year 438, calls him "mentally disturbed."
Polemius was assigned to Eucherius, bishop of Lyon (ancient Lugdunum), and produced the calendar for him. Because fixed Christian feasts were still few in number, Polemius faced the challenge of fulfilling the conventions of a traditional Roman calendar with named holidays while "disinfecting" it of the Imperial Roman and other festivals now regarded as "pagan." Although the Calendar of Filocalus in 354 had recorded the traditional religious holidays freely, by the time of Polemius the Christian state had begun to legislate against other religions and to divorce Rome's religious heritage from the culture and civic life of the Empire. Polemius, who had probably consulted the Calendar of Filocalus, filled gaps with meterological and seasonal markers, and the "Egyptian Days," days considered unpropitious for new undertakings and for certain medical practices. Bede was among those who drew information from it.
In Polemius's calendar, the word ludi, "games" in classical Latin, means more specifically theatrical performances, while circenses is used for chariot races. His work provides significant examples of Gallo-Romance vocabulary, regional variations of the Latin language, and local survivals of Gaulish words.
The calendar 
The format used by Polemius for the most part followed the conventions of Roman calendars, with days arranged in parallel columns under the name of the month, and each day noted on a separate line. Column 1 numbers the days of the month. Column 2 identifies any special days, not only traditional Roman and Christian holidays, but also the birthdays of emperors, and days when consuls and praetors took office. Column 3 gives weather conditions; Columella's 1st-century treatise on agriculture may have influenced the inclusion of references to weather. Polemius also provided information from his own research, such as the birthdays of Cicero, Vergil, and a Faustina who was the divinized wife (diva) of an Antonine emperor.
- emperors and usurpers;
- the Roman provinces;
- animal names, spread out over two months;
- a table for calculating the date of Easter and the phases of the moon (not extant);
- buildings and topographical features of Rome;
- fabulae poeticae ("poets' tales");
- a breviary of Roman history;
- "a register of animal voices";
- weights and measures;
- meters of poetry (not extant);
- a survey of philosophical sects (not extant).
- Giusto Traina, 428 AD: An Ordinary Year at the End of the Roman Empire (Princeton University Press, 2009, from the original Italian edition of 2007), p. 180.
- Mary Beard, J.A. North, and S.R.F. Price, Religions of Rome: A Sourcebook (Cambridge University Press, 1998), p. 69.
- J.N. Adams, The Regional Diversification of Latin, 200 BC–AD 600 (Cambridge University Press, 2007), p. 295.
- David Paniagua Aguilar, "Adis: A Ghost Latin Zoological Term," Bulletin Du Cange 65 (2007), p. 227.
- Traina, 428 AD, p. 180.
- Adams, Regional Diversification, p. 295.
- Traina, 428 AD,p. 180.
- Traina, 428 AD, p.180.
- Faith Wallis, "Medicine in Medieval Calendar Manuscripts," in Manuscript Sources of Medieval Medicine: A Book of Essays (Garland, 1995), pp. 106–107.
- Michele Renee Salzman, On Roman Time: The Codex Calendar of 354 and the Rhythms of Urban Life in Late Antiquity (University of California Press, 1990), p. 235.
- Salzman, On Roman Time, p. 4.
- Wallis, "Medicine in Medieval Calendar Manuscripts," pp. 106–107.
- Bruce Eastwood, Ordering the Heavens: Roman Astronomy and Cosmology in the Carolingian Renaissance (Brill, 2007), p. 269.
- Faith Wallis, Bede: The Reckoning of Time (Liverpool University Press, 1999), p. 52.
- Wallis, Bede, p. 52.
- Adams, Regional Diversification, pp. 295ff.
- A.D. Lee, Pagans and Christians in Late Antiquity: A Sourcebook (Routledge, 2000), p. 146.
- Michael Maas, John Lydus and the Roman Past (Routledge, 1992), p. 53.
- Salzman, On Roman Time, p. 139.
- Salzman, On Roman Time, p. 14.
- For examples of the kinds of information Polemius provides, see Lawrence Richardson, A New Topographical Dictionary of Ancient Rome (Johns Hopkins University Press, 1992), passim.
- Lists as described by Aguilar, "Adis," p. 227; Adams, Regional Diversification, p. 295.
- Wallis, Bede, p. 42.