Menachot 37

A full set of tefillin includes two boxes, each called a bayit, with the required scrolls inside it, as well as two sets of straps. This works out well for those who have one head and at least one arm. But on today’s daf, the rabbis’ love of edge cases takes a more creative turn.

Peleimu raised a dilemma before Rabbi Yehuda HaNasi: One who has two heads, on which does he don tefillin? 

A number of two-headed creatures appear in mythologies from many cultures. In Welsh folklore, the giant who fights Jack (of beanstalk legend), is described as a two-headed giant named Thunderdell. Geographically closer to the Babylonian rabbis, Greek mythology tells us that the three-headed dog Cerberus, who guarded the Gates of Hades, had a less famous (but probably still cute) two-headed brother, Orthrus, who guarded the Cattle of Geryon. Of course, neither (non-Jewish) giants nor dogs are obligated in the mitzvah of tefillin. But what about a Jewish man with two heads? Peleimu doesn’t suggest that both heads need tefillin. The question is just which head gets the mitzvah. So how does Rabbi Yehuda HaNasi answer his question?

He said to him: Either get up and exile yourself or accept upon yourself excommunication.

In many cases, the rabbis systematically discuss absurd cases to stress test law. But here, Rabbi Yehuda HaNasi is neither edified nor amused. The Talmud doesn’t explicitly tell us Peleimu’s intentions, but Rashi suggests that Rabbi Yehuda HaNasi thinks Peleimu is trying to annoy him, or perhaps trick him. But then, lo and behold:

In the meantime, a certain man arrived and said to him (Rabbi Yehuda HaNasi): A firstborn child has been born to me who has two heads. How much money must I give to the priest? A certain elder came and taught him: You are obligated to give him ten sela.

Peleimu’s question is almost immediately validated by the announcement of a newborn baby boy with two heads. Indeed, while rare, there is a condition of conjoinment that the medical establishment calls dicephalic parapagus. So what was this second halakhic question from the new father? Numbers 18:16 sets out the details of the mitzvah of pidyon haben, the redemption of the firstborn. When an Israelite woman gives birth to her first child and that child is a boy, the family is required to redeem their son from the priests at the cost of five selas. In this case, the child is a firstborn so must be redeemed, but at what price? We learn elsewhere that in the case of twins, only the firstborn child counts as the first-born for the purposes of pidyon haben. But this isn’t twins. An unnamed sage then explains that this child is treated like two firstborns and the father consequently owes ten selas.

The Talmud continues to discuss how to calculate the amount given to the priest, but it never returns to Peleimu’s question. But that Peleimu’s question is almost immediately validated by a real-life example invites us to consider the world with new eyes, and increased wonder. 

The use of edge cases — whether or not they are intended to be theoretical — reminds us that the world is more vast than we can imagine. A world in which conjoined twins can be born healthy, and can grow up to be obligated in the mitzvah of tefillin, challenges us all to think about how we can create the infrastructure through which those with a range of bodily differences can be fully included in Jewish life.

Read all of Menachot 37 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on February 17, 2026. If you are interested in receiving the newsletter, sign up here.