This is a bronze follis of Constantine the Great, Emperor of Rome under whose aegis Christianity was at last legitimized and Christmas was first recorded as being celebrated – in Rome on December 25th of the year AD 336 (as is the customary date for many).
The Reverse shows a Roman military-style standard as a Labarum – surmounted by the greek symbol chi-rho or Christ. There is a serpent at the foot representing, for the ancient Romans, rebirth and fertility; a symbol of Asclepius the greek God of Healing. Beneath are the letters CONS, for the coin was minted in Constantine’s own city of Constantinople. And across the field it reads SPES PUBLIC. The Roman goddess SPES was the goddess of spiritual Hope and one of the divine Virtues of the imperial Augustus.
The message of the Reverse is, perhaps, something like “Through the power of Christ, the force of the Augustus Renews the Hope of the Public.”
Although opinions do differ widely. Most associate the serpent with evil and sin as is also customary in Christian tradition and Christ overcomes all evil. Many suggest the coin represents the execution of Licinius in 324. Constantine had been keen to portray his christian-friendly, Co-Emperor Licinius as fully Pagan. The serpent would make sense. As would the Labarum spearing it.
Thank you for the image [source being traced ]
Note: since I wrote this experts have pointed out that the coin I’ve shown is actually one of the master forgeries of the SPES PVBLIC type.
See this article here: Highly Deceptive Forgeries of Constantine’s SPES PVBLIC Coinage. (2009: Lars Ramskold. The Celator, Dec. 2009, pp. 18-32)
Comments and corrections are very welcome!
Here’s the SPES PVBLIC from Wildwinds
Constantine AE follis. CONSTANTINVS MAX AVG, laureate head right / SPES PVBLIC, chi-rho atop standard of 3 medallions impaling snake, A to left. Mintmark CONSA.
Constantinople RIC VII 19
Thank you Wildwinds for image and attribution text