From an Art History perspective the stylistic change between the 260's and the 280's was unprecedented in Roman history. Instead of realistic portraiture which was the norm up until that point Diocletian introduced a whole new style of representing the Augusti and Caesars on art and coins. Similarly, court procedure was altered so that those in the emperor's presence were required to perform proskynesis. One supposes that the challenges faced by the Empire at that time were so extensive that it necessitated a drastic upheaval, but what ultimately led to this stylistic revolution is unknown, other than a consolidation of power which ruled out previous idioms.
I find this subject fascinating too! I suspect that the process was more gradual than it's sometimes represented to be. This can be seen on the following coin of Probus, which foreshadows both the austere tetrarchal style (as do many coins of the late 3rd century), as well as the shift in court ethos: note the "INV" (Invictus) in the title, linking Probus to the unconquered sun, Sol. This surely must have been accompanied by some abasement of his subjects!
Here is my page on portraits of the four emperors of the first tetrarchy on GENIO POPVLI ROMANI coins, organized by mint: http://augustuscoins.com/ed/tetrarchy/bymint.html There are linked pages organizing them by emperor instead. Perhaps surprisingly, the one I think is the most expressive and realistic is from the London mint: Maximian London 28 mm. 9.89 grams. IMP MAXIMIANVS PF AVG RIC London 23b
I found the OP photos pretty dark so I brightened them: Maybe @ancient coin hunter can tell us if these look more, or less, like the coin.
I only have two tetrarchs in my collection. I wouldn't say both coins are austere in style, though the Maximian is definitely a typical coin of the era in theme and appearance. However, mine boasts a particularly fine style that definitely ranks up there amongst the finest of the era. The Galerius is more austere in terms of artistry. Maximian (Senior Emperor) Galerius (Maximian's junior partner)
I'd argue that the trend toward more cookie cutter emperors was started by Claudius II and really only interrupted by Tacitus. Just take that bronze bust on Wikipedia for the Claudius II entry - seemingly every few months the attribution changes from Claudius to Aurelian to Probus and then back again. Diocletian's artistic reforms were of course a natural extension of the then 15 year trend which continued basically until the early years of the Byzantines. I have all of the Tetrarchs except for the usurpers, but this Constantius I is my favorite because he is actually making a facial expression ... an expression like he needs more fiber in his diet, but an expression nonetheless!
I suspect that the portraits of the tetrarchs really is an extension of the "military style" portraiture with its emphasis on an image of a close cropped hair and beard. First started by Maximinus I Thrax carred on by emperors such as Philip I, Gallus, and later by emperors like Claudius II it reached it apogee under the Tetrarchy. What does make the images different under the Tetrarchy is the effort to create a standardized power image more or less devoid of individuality.
That's a really interesting page. Thanks for putting it together. To my eye the general trend appears to be that the portraits get more stylized as you move eastward. Compare the two portraits below, first from Trier, second from Antioch: Diocletian Treir mint, A.D. 301-305 Obv: IMP DIOCLETIANVS AVG Rev: GENIO POPV-LI ROMANI - Genius, modius on head, naked but for chlamys hanging from shoulder, holding patera and cornucopiae PTR in exergue; S in left field, F in right RIC 582a 26mm, 7.7g. Maximinus II ("Daia") Antioch mint, A.D. 312 Obv: IMP C GAL VAL MAXIMINVS P F AVG Rev: GENIO AVGVSTI - Genius, modius on head, naked but for chlamys hanging from shoulder, holding head of Sol and cornucopiae ANT in exergue; [star] in left field, S in right RIC 164b 22mm, 4.7g.
Yes, agreed. There was a hidden Finnish Dynasty that ruled the Roman Empire at that time. I am proud to have Finnish in my blood. I better put a smiley here to denote satire, or someone is gonna go ape! GALERIUS: RI Galerius 293-308 AE30mm Folles Ticinum mint Moneta 12g