The Book of Kings reports: “And he [Solomon] made the ‘Molten Sea’ (a copper tank used for the priests) of ten cubits from brim to brim around in compass, and five cubits in height and a line of thirty cubits compassed it round about” (I Kings 7:23).
The sages mention the “Molten Sea,” in a conversation about circumference: “Whatsoever has a circumference of three handsbreadths is one handbreadth in diameter. Whence are these calculations deduced?” (Talmud Eiruvin 14a) After quoting the text of I Kings 7:23, the rabbis debate the accuracies of these measurements. Rabbi Jochanan set forth the question: “But surely there was [the thickness of its] brim (which would increase the diameter),” to which Rabbi Papa replied: “...But there was [still] a fraction at least? When [the measurement of the circumference was computed it was that of the inner circumference” (ibid.).
The rabbis were aware that the measurement of the ratio of a circumference to its diameter is never perfect. It is, in fact, the irrational, seemingly-unending number of Pi: 3.14159....
And the fact that Pi appears unending is beautiful in its connection to a circle, which has no beginning and has no end and is the Jewish metaphor for the cycle of life.