From this Blog from our own Reb Chaim Haqoton Shlit"a:
Squared vs. Rounded Tablets
There is a custom in many synagogues to display a representation of the Tablets (Luchos) containing the Ten Commandments at the front of the synagogue sanctuary. These images are generally placed on top of the ark containing the Torah Scrolls and/or on the curtain covering the ark. In many renditions of the Tablets, they shaped as regular rectangles or squares, but in most renderings, they are rounded on top. In recent times, several Rabbinic figures have expressed their opinions regarding this matter.
The Tablets’ Dimensions
The Babylonian Talmud records the dimensions of the Tablets as six handbreadths long, six handbreadths wide, and three handbreadths thick. The Jerusalemic Talmud offers a similar description, noting that the Tablets were three handbreadths wide. All in all, both Talmuds seem to agree that the Tablets were square prisms because they note the Tablets’ dimensions in a linear way, without specifying that the Tablets were rounded.
Furthermore, in the ensuing discussion in the Babylonian Talmud, the Talmud proves from the Tablets’ dimensions and the dimensions of the Holy Ark that when the Tablets were placed in their ark, the ark was completely filled exactly to capacity. Since the Holy Ark was a cube prism, the Talmud calculations can only work if the Tablets were also squared. If the rounding was done within the square dimensions of the Tablets, then there would be slightly more room in the Ark, while if the rounding was done outside of the square dimensions of the Tablets, then the Tablets would be too big to fit into the Ark.
While the Talmud stops short of explicitly mentioning that the Tablets were squared, Rabbeinu Bachaya (1255–1340) does so in his commentary to the Torah. The Torah tells that at Marah, HaShem “offered [the Jews] a decree (chok) and ordinance (mishpat)”. Rabbeinu Bachaya explains that “decree” in this context alludes to the Tablets. He justifies this association by noting that according to the dimensions of each squared Tablets given in the Talmud, the volume of each Tablet equals one-hundred and eight cubic-handbreadths (6x6x3 = 108). The number one-hundred and eight equals the word “decree” (חק) in numerical value (Gematria). Similarly, Pirush HaRokeach twice mentions that the total volume of the twin Tablets is two-hundred and sixteen. He seemingly arrived to this conclusion the same way as Rabbeinu Bachaya (only doubling the formula to calculate both Tablets together). In short, by calculating the volume of the Tablets as simply a function of its length, width, and thickness, these sources clearly understood that the Tablets were perfectly squared, which, in fact, Rabbeinu Bachaya wrote explicitly.
Rejecting the Notion of Rounded Tablets
In two responsa about this topic, Rabbi Eliyahu Katz (1916–2004), Chief Rabbi of Slovakia and later of Beer Sheva, writes that the Tablets given at Mount Sinai were definitely squared, not rounded. He notes that it seems Christian artists like Michaelangelo (1475–1564) and Rembrandt (1609–1669) were the first to introduce the notion of rounded Tablets and their widespread portrayals of the Tablets in such a permeated Jewish culture, even though it contradicts tradition.
Nonetheless, since it has become a widespread practice even in Jewish circles to portray the Tablets as having a rounded top, Rabbi Katz proposes an interesting theory to justify its prevalence by ascribing a more “Jewish” origin to the practice. He notes that in certain ancient Tunisian synagogues, there are images of the Tablets with three crowns atop them. These crowns ostensibly represent the three crowns which adorn the Jews: the Crown of Torah, the Crown of Priesthood, and the Crown of Kingship. While earlier images of the Tablets were supplemented with these three crowns, over time, the meaning of these three crowns was forgotten and people began to assume that the Tablets themselves were rounded on top. Based on this explanation, Rabbi Katz proposes that the old Tunisian custom should be restored with three crowns on top of the Tablets and a line of demarcation to separate the crowns from the Tablets so that the observer would realize that the Tablets themselves were not round.
Following Rabbi Katz's suggestion, MK Yaakov Margi (Shas), who formerly served as the chairman of the local religious council in Beer Sheva, changed his council's official logo from a rounded depiction of the Tablets to a squared one.
Similarly, the late Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson (1902–1994), spoke strongly against those who depict the Tablets as rounded on top and actively campaigned for an accurate portrayal of the Tablets.
Justifying the Common Practice of Rounded Tablets
In one of his responsa, Rabbi Yisroel Yaakov Fisher (1928–2003), Chief Rabbi of Badatz Eidah Chareidis in Jerusalem, defends an author who came under attack for including in his book an image of the Tablets as rounded. He writes that the Talmud never mentions whether the Tablets were squared or rounded and there is no clear proof to either approach (however, see above). Furthermore, he expresses his bewilderment as to why that author’s book came under attack, but no one ever complained about the multitude of synagogues across Jerusalem which portray the Tablets as being rounded. Instead, Rabbi Fisher proposes that there is justification for portraying the Tablets as round and the custom should not be discontinued.
He begins by offering an interesting proof to the assertion that the Tablets were in fact rounded, not squared. The Jerusalemic Talmud in several places states that when HaShem created the world during the Six Days of Creation, squares did not naturally occur, implying that everything created then was circular, not squared. Additionally, the Mishnah teaches that the Tablets were created during the Six Days of Creation. By putting together these two sources, Dayan Fisher concludes that according to tradition the Tablets were completely rounded (even the bottom!), not squared.
Rabbi Katz rejects this proof by noting that the Talmud itself qualifies its assertion about squares in nature by restricting it to living creatures (and perhaps also foods), but not all elements of creation. Furthermore, he notes that the same Mishnah teaches that HaShem created the script of Lashon HaKodesh during the Six Days of Creation, yet the script of Lashon HaKodesh surely contains squared figures such as the final mem (ם).
Furthermore, Dayan Fisher argues that even if the Tablets were actually square, there is another reason to continue the custom of rounding the Tablets. The Talmud mentions a prohibition of constructing replicas of the Holy Temple and its paraphernalia. While some commentators restrict this prohibition to only those elements listed there in the Talmud (namely the Sanctuary, the Hall, the Courtyard, the Shulchan, and the Menorah), others, including the Galician Rabbi Yosef Babad (1801–1874) understand that this prohibition applies to anything for which the Torah prescribes certain dimensions. Dayan Fisher understood that the Tablets are therefore included in this prohibition (and explains that even though the Torah does not mention its dimensions, the Talmud does). Accordingly, he supports the custom of rounding images of the Tablets so that the distorted image would not fall under this prohibition.
Nonetheless, Rabbi Katz disagrees with Dayan Fisher’s assessment of the matter and contends that only what is mentioned in the Talmud is forbidden to be replicated, thus excluding the Tablets, which are omitted from the Talmud’s list. Furthermore, argues Rabbi Katz, this prohibition only applies to one who constructs these elements in their prescribed dimensions, but replicas of the Tablets do not generally match the dimensions of the Talmud. Even if one was particular to construct the Tablets at six handbreadths wide and long, they do not usually also make sure to have the Tablets three handbreadths thick. Since this change already removes the prohibition of replication, there is no need to further distort the image of the Tablets by rounding off the tops.
In his final note on the topic, Dayan Fisher notes that since it is unclear whether the Tablets were squared or rounded, the custom is to square the bottom and to round the top, thereby surely altering the image from the original so as to completely avoid the prohibition of replicating components of the Temple.
Rabbi Elazar Menachem Man Shach (1899–2001), Rosh Yeshiva of Ponovezh and leader of World Jewry in his time, was once asked by the board of a synagogue which was designing its building whether they should make the Tablets rounded or squared. He responded by writing that he sees that most synagogues have the Tablets rounded, even though in truth, the historic Tablets were squared. He concludes that while it seems that the accepted custom is to round the Tablets, the Steipler Gaon, Rabbi Yaakov Yisroel Kanievsky (1899–1985) instructed that the Kollel Chazon Ish should have squared Tablets. In his conclusion, Rabbi Shach defers to Rabbi Kanievsky’s position and recommends that the synagogue have squared Tablets, not rounded ones.
King Solomon advises about the Torah and Mitzvos, “write them on the tablets of your heart” (Proverbs 7:2). Based on this, Radaz, Rabbi David ben Zimra (1462–1572) explains that the Tablets of the Ten Commandments represent the heart of a person in many different ways. Just as the word of HaShem is eternally inscribed on the Tablets, so should a person eternally inscribe in his heart the will of Hashem. Following this line of reasoning, Rabbi Chaim Friedlander (1923–1986), the Mashgiach of Ponovezh, explains that for this reason the Tablets are traditionally rendered as rounded on the top , i.e., “heart-shaped”.