What have we found? We have found seven places in Israel where Jews put zodiac wheels, Helios, the four seasons, a panel of synagogue objects, and sometimes remembrance of righteous ancestors in mosaic on the floor of their synagogues. For the record, we have never found a zodiac in a Jewish context outside of Israel, and every zodiac found in Israel was in a synagogue.I do disagree with the last point ("it left no literature"). Anyone who has worked with the Talmudic-era Hebrew magical treatise Sefer ha-Razim (The Book of the Mysteries) will not be surprised at all by the zodiac symbolism or use of pagan gods in these synagogue mosaics. The Talmudic tradition is hostile to such magical and mystical traditions (although perhaps not quite as hostile as one might expect). But the hostility is consistently couched in a way that indicates that such traditions existed in Judaism were popular enough to require refutation. Sefer ha-Razim (on which more here and here) includes a fair amount of astrological symbolism, and some of the rites involve the making of images and even the invocation of the pagan god Helios. Yet the practitioners of these rites are clearly – in their way – religious Jews. It's hard to tell how they justified the pagan influences in their own minds. I suspect they thought along the lines of the pagan gods being angels under the control of the one true God, astrology just being one set of natural laws created by that God in his universe, and magic being a perfectly appropriate technology as long as it did not involve actually worshiping anyone but the true God. In this context, the synagogue mosaics preserve fairly mild uses of the same traditions.
That fact tells us what we already knew: that these zodiacs were certainly not just decorations or pretty pictures. Nor were they attempts at astrology (predicting the future) or astronomy. The Ark, candelabrum, shofar, etc. were put in synagogues (and on tombstones, lintels, doorposts and catacombs), the most serious of places for the Jewish community. And the inscriptions on the zodiacs themselves were invariably in Hebrew, even if the common languages of the day, Aramaic or Greek were added. That is, the zodiacs were important and meant something to the people who made them. The question is: What? It is time to suggest some conclusions.
The evidence indicates that we are in the presence of a mystical Hellenistic-Byzantine Jewish tradition, a tradition that Talmudic Judaism either ignored or suppressed,29 a tradition we would not know anything about (for it left no literature) were it not for the discovery of this artwork, these symbols.30 The mosaics are in fact the literature of the movement. We need to learn how to read them.
You can read Sefer ha-Razim in English translation by Michael A. Morgan in Sepher Ha-Razim: The Book of the Mysteries (SBLTT 25/SBLPS 11; Chico, Calif.: Scholars Press, 1983). I am currently working on a translation based on much better manuscript evidence for volume two of the More Old Testament Pseudepigrapha Project.