Two of the statues I recently viewed in Italy really convinced me (as they have others such as Fleischer and LiDonnici) that the protuberances were usually understood not as breasts but as part of the costume which decorated the statue of Artemis Ephesia.
This is a statue you can now see in the Capitoline museum in Rome. This statue has many of the same characteristics that we found in the other statues in my series here (arrangement of arms and legs, decoration of Artemis’ outfit with animals) with one very important exception: the use of two different colours of stone in the carving of the statue. The artist that carved this statue, those who commissioned it, and likely many who viewed it considered the protrusions on Artemis’ front not as breasts (which would need to be black here to match the skin of her feet and arms) but as part of the clothing decoration. Clearly these are not breasts. As Fleischer and others note, it is likely that the artist was representing an earlier statue of Artemis Ephesia (perhaps a statue of dark wood) which was literally dressed in special garments on particular occasions (dressing and feeding statues was somewhat common in certain cultural circles in antiquity). The artist chose to distinguish the earlier statue itself from the clothing and paraphernalia that decorated that statue by using two different colours of stone, and the bumps on her front are part of the costume here.
That this understanding of the protrusions was not just an anomaly is confirmed by another artist’s rendition found in Neapolis, which is now preserved in the national museum in Naples (inventory no. 6278):
So although church fathers such as Jerome and Minucius Felix later tended to generalize about the “multi-breasted” Artemis (Minucius Felix, Octavius 22.5; Jerome, Commentary on the Epistle to Ephesus proem), this characterization in late antiquity arose less from common perceptions among worshippers of this goddess and more from Christian propaganda aimed at presenting “paganism” as ridiculous or bizarre. What exactly these objects are is at this point generally unanswerable, but what is clear is that they are part of Artemis Ephesia’s outfit, not her body.