The fact that there were two of them symbolised the harmony between man’s double duty, with the first tablet representing duty to God and the second, duty to man. This symmetry was made possible by having five commandments on each tablet but required the fifth (respect for parents) to be interpreted as a duty to God.
No-one, however, is certain as to the exact shape of the tablets. The great rabbinic compilations, the Babylonian and Jerusalem Talmuds, record conflcting traditions. The Babylonian view was that the tablets were approximately 22 inches square, whereas the Jerusalem envisaged them as oblong, about 22 inches by 11.
Neither thought of them as having arched or domed tops, though this is the way they have generally been depicted for centuries. They entered Christian art in Italy, where they had the form of two rectangles. According to GB Sarfatti they acquired an arched top due to the influence of the dipytch, a register folded into two leaves with curved tops which was used by the Romans to list the names of magistrates and later by the Catholic Church to record the names of deceased people commemorated with oblations. This design spread to many branches of religious art and architecture and made its way into the arched windows of abbeys and churches.
As we can see from a statue in Lincoln Cathedral and from other
contemporary sources, even old Haggadot, the Jewish badge in medieval England took the form of the tablets of the Decalogue.
Jewish communities themselves began to depict the Ten Commandments in about the 13th century and the Decalogue eventually became a widespread feature of synagogue buildings, almost always with the rounded shape introduced by the Christian artists of the Middle Ages.
These days some Jewish artists prefer the square or rectangular shape known in the time of the Talmud, but this is still the exception
rather than the rule. The Ten Commandments figure in many areas of
Jewish ritual art, ranging from Ark curtains to tallit clips. They often figure on Torah breastplates and Chanukah menorot. Almost
everywhere they top the synagogue ark. In some places the m’chitzah (the partition between men’s and women’s seating) is decorated by a line of joined tablets of the commandments.
Though there is a general view that the characteristic Jewish symbol
is the Magen David or Shield of David, the Decalogue is more ancient and has greater authenticity. Its theological significance lies in its balancing of the inner and outer dimensions of a Jew’s being.