Literary critic Adam Kirsch is reading a page of Talmud a day, along with Jews around the world.The most common reason why people convert to Judaism today, I would guess, is because they want to marry a Jewish spouse. Such conversions are a sign of the amazing acceptance that Judaism enjoys in America, compared to the stigma it labored under for most of Western history. For a Christian to marry a Jew in medieval Europe meant stigmatization, isolation, perhaps even violence, as it does in many parts of the Muslim world today. For us, it is simply a personal choice, even a laudable demonstration of spousal loyalty. It was surprising to learn in this week’s Daf Yomi reading, then, that according to the Talmud, converting out of love is actually forbidden. “Both a man who converted for the sake of a woman and a woman who converted for the sake of a man,” we read in Yevamot 24b, “they are not converts.” (The Koren Talmud’s notes make clear, however, that this is not how conversions are actually regulated in practice today; as often, the law has evolved significantly since the Talmud was written.)The Talmud’s logic seems to be that conversion must not be undertaken for the sake of any personal advantage or reward, but strictly out of belief in the truth of Judaism. That is why the rabbis list converting for love alongside other kinds of compromised conversions, such as “one who converted for the sake of the king’s table”—that is, in order to receive financial support or career advancement from a Jewish government.The same holds true of those who convert to escape punishment. In the Second Book of Kings, for instance, we read that after the conquest of the Kingdom of Israel and the exile of the Ten Tribes, the king of Assyria imported new peoples—known as Samaritans, or in Hebrew Kutim—to populate the land. Because these new arrivals didn’t know the right way to worship God, he sent flocks of lions to attack them. Not until they learned from a priest what God required did the lions leave them alone. The Talmud insists, however, that the Kutim who embraced Judaism out of fear of lions were not true converts. Neither were the Persians who converted from fear of the vengeful Jews who were turned loose on them at the end of the Book of Esther.All these people, the rabbis say, “are not converts unless they are converted again at this time.” Here the Gemara makes an obvious objection: Surely those Samaritans and Persians couldn’t be reconverted “at this time,” since they lived centuries earlier. “Rather, say: Like at this time,” the Gemara clarifies: That is, at a time of Diaspora and Jewish weakness, when joining the Jewish people entails risks and no rewards. Only under those circumstances is it clear that a convert is embracing Judaism for the sake of heaven, rather than hope of benefit. For this reason, “they did not accept converts in the days of David or in the days of Solomon,” at a time when the Israelite kingdom was rich and powerful, and becoming Jewish might be considered a desirable change. Nor will converts be accepted “in the days of the Messiah,” when Jewish glory and power are restored.How does this discussion of converts find a place in Tractate Yevamot, which deals with the laws of levirate marriage? The connection can be found in the mishna on Yevamot 22a, where the rabbis explain the legal status of different types of children. The obligation for a man to marry his dead brother’s widow—his sister-in-law or yevama—only applies if the brother has died without producing children. The levirate marriage is meant to produce offspring that will legally and spiritually be considered the dead man’s heirs. That is why a widow who is an aylonit—incapable of bearing children—is not subject to this obligation. The same holds true, we learned this week, if the dead man was a eunuch, since he would have remained childless even if he had lived.If the dead man has produced children, it would seem the levirate obligation is canceled. But, the Talmud explains, there are different categories of children. Those produced in legal wedlock are of course legitimate, and they invalidate the levirate obligation. But what about if the dead man had children outside of his marriage, or by rape, or through a legally forbidden relationship such as incest? Do those children also count as offspring for the purposes of the levirate obligation? The answer, the mishna says, is yes: “Anyone who has a child of any kind, that child exempts his father’s wife from levirate marriage.” Even a mamzer, an illegitimate child, “is his child in all respects,” including the fifth-commandment obligation to honor his father: “And that child is liable to receive capital punishment if he strikes his father or curses him.”There are only two types of offspring who are not legally considered true children: “a child born from a Canaanite maidservant or from a gentile woman.” The Talmud goes on to explore the reasons for this rule. Why should it be worse for a Jewish man to marry a gentile woman than to marry a Jewish woman who is forbidden to him by the laws of incest? Why is the offspring of the latter relationship, though a mamzer, considered a true child, while the offspring of the former relationship is not considered a child at all? The reason, the Gemara suggests, is that a forbidden woman is forbidden only to one specific man—say, because she is his wife’s sister—but she is permitted to marry any other Jew. A gentile, on the other hand, cannot enter into marriage with any Jew at all.But in fact, the Gemara goes on to counter, there is a way for a gentile woman to become marriageable: All she has to do is convert to Judaism. Doesn’t this mean that she is legally akin to other forbidden women, who are not forbidden forever and always, but only under certain conditions? But the rabbis deny the parallel. “When she converts, she is a different body,” they say: Conversion creates a new legal person, who did not exist before. It is only this new person who is marriageable, not the old, gentile version of her who has ceased to exist.Thus when a Jewish man has children with a gentile woman, they are considered not his children at all, but only hers: “Your son from a Jewish woman is called your son, but your son from a gentile woman is not called your son, but her son.” The same does not hold true, however, if the genders are reversed. The Koren Talmud’s notes cite the Shulkhan Arukh, a later, authoritative code of Jewish law, to this effect: The child of a gentile father and a Jewish mother is Jewish. Here we can see that Jewishness is inherited matrilineally, so that it is the religion of the mother that counts.But this is not the end of the discussion. It would be easy to imagine a case where a Jewish man fell in love with a gentile woman and then she converted in order to marry him; or where a man fell in love with a Canaanite slave and then set her free so they could be together. But in Yevamot 24b, the mishna rules that such marriages are invalid: If a man is once suspected of an illicit sexual relationship with such a woman, he cannot marry her later on, because such a marriage would retroactively confirm the suspicion that he had sinned. Still, the law is not overly harsh, since “if he did marry her, the judges of the court do not remove her from him.” This is one of several places in Yevamot where the rabbis have made a distinction between marriages that are legally allowed and marriages that are tolerated in fact. The rabbis seem to have been too humane, or too pragmatic, to go around breaking up consensual marriages on technical legal grounds.The same leniency does not apply, however, to cases of adultery. Say a married woman is widely suspected of having an affair with another man and then divorces her husband and marries the putative lover. In this case, the rabbis say, judges must intervene to separate them, since their marriage seems to confirm the rumors that they had previously had an adulterous relationship. In this situation, rumor is taken to have probative value. Indeed, the rabbis even offer a definition for when a rumor is widespread enough to be taken seriously: “At what point is it considered to be a persistent rumor? Abaye said: My mother told me: A rumor in the city lasts a day and a half.” However, a rumor can be dismissed entirely if there is reason to think it was started maliciously, by a person’s enemies. All this sounds strange from the perspective of American law, where hearsay is strictly forbidden as evidence. But then, the rabbis were in the business of regulating not just actions but reputations—particularly women’s reputations.***To read Tablet’s complete archive of two years of Daf Yomi Talmud study, click here.Adam Kirsch is a poet and literary critic, whose books include The People and the Books: 18 Classics of Jewish Literature.