The Shabbat immediately preceding the beginning of the month of Adar is called Shabbat Shekalim, referring to the commandment we read about in the special maftir of this Shabbat: “This shall each who undergoes the count give: half a shekel of the sanctuary—twenty gerahs to the shekel—half a shekel, a donation to the Lord” (Exodus 30:13).

Why does the Torah tell us that a shekel is twenty gerahs? What does this add, particularly if, as Rashbam (R. Samuel b. Meir) and many other commentators explain, the gerah was “a type of coin”? Is there any advantage to saying “half a US dollar—a hundred cents to the dollar”? Why not suffice with simply stating the name of the coin – half a shekel – if the objective is to establish a symbolic item to be used for taking a census? And if the intention is the establishment of a tax, why not simply state the value, i.e. ten gerahs? These issues become even more puzzling when we read about the levying of the tax after the return to Zion: “We also lay upon ourselves the obligation to charge ourselves yearly with the third part of a shekel for the service of the house of our God” (Nehemiah 10:33).

The verse in Nehemiah seems to contradict the verse we read in this week’s maftir. Some commentators, like Abraham Ibn Ezra, explained that the verse in Nehemiah did not refer to the “half-a-shekel” but rather to a special surcharge that was added to the half-shekel tax.

As Nahamanides correctly points out, the answer is not that there were different levies, bit that there were different shekels. The gerah was not the name of a coin that represented a fixed value, but rather it was a unit of weight. In the early period, a shekel weighed twenty gerahs. In the later, Persian period, a shekel weighed thirty gerahs. Thus, we have an answer to why the tax was set at a third of a shekel rather than half a shekel in the Second temple period. The half shekel referred to in Exodus weighed ten gerahs, and ten gerahs was the weight of a third of a shekel at the time of Nehemiah.

1. The mitzvah of half-a-shekel comprises two elements: one is the symbolic “half shekel”, while the other is the value of ten gerahs of silver. If we assume that the Torah does not intend to teach us a lesson in economics or currency exchange rates, what value lessons are we supposed to learn from the inclusion of these two elements?

2. After the return to Zion, it was necessary to decide which element to prefer in light of the change in the value of the shekel. What was to be given preference, the concept of “half-a-shekel” or the value of half of “twenty gerahs”? What can we learn from the decision to establish a tax of one third of a shekel?

3. Does the fulfilment of the mitzva of “half-a-shekel” by means of a third-of-a-shekel tax reflect a fundamental approach to the nature of mitzvot? Can it teach us something about the relative importance of the symbolic value of mitzvoth as opposed to their practical importance?