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The first mishnah of Kiddushin teaches how a woman is “acquired” in marriage and how she “acquires” herself, that is to say, how she becomes free to marry another man. The mishnah also teaches how a “yevamah” is “acquired.” A “yevamah” is a woman whose husband has died without any children. According to the Torah she must either marry her husband’s brother or perform halitzah, the release from the obligation to her brother-in-law.
A man can betroth his wife in any one of three ways. The first is by giving her a small amount of money and saying to her “Behold you are betrothed to me with this money.” Bet Shammai and Bet Hillel debate how much money is needed to effect betrothal. What is crucial is that both a denar and a perutah are small amounts of money; a perutah is almost valueless. These are not representative of a woman’s true value, which is clearly much greater. Rather they are symbolic, especially in Bet Hillel’s opinion. To this day, nearly all betrothals are effected through money. Since the Middle Ages and perhaps earlier, Jews have used rings to effect betrothal. This custom was originally a Christian custom. In the Talmud rings are never used.
The second way is for the husband to write her a document in which it is stated, “Behold you are betrothed to me.” This document is not to be confused with a ketubah, although some scholars posit that they are both derived from common origins and that originally they were written together.
The thirds means of betrothal is sexual relations. This act must be done with the intent of betrothal. No one holds that casual intercourse can effect betrothal. The thornier problem is whether or not sexual relations between a couple “living together” can effect betrothal. Most modern halakhists rule that it does not, although there are some who hold that couples who live together with the intent to form a familial type of unit do require a get in order to separate.
A woman becomes halakhically separated from her husband either by divorce or by death. Without one of the two, any relations that she has with another man will be considered adultery.
The dead husband’s brother-in-law “acquires” his brother’s widow through sexual intercourse. The yevamah is not acquired by money, as a woman would be in cases of normal betrothal.
The yevamah is free to marry another man if she performs halitzah with the yavam. Alternatively, if the yavam dies (in a situation where there is only one yavam) she also may marry anyone she so chooses. Note that once she is married she is considered a normal wife, and she “acquires” herself through the death of her husband or through divorce.
The first couple of pages of Kiddushin are intensely interested in the particulars of the language of the Mishnah, and not in its content. Since the Geonic period (the period that immediately followed the Talmudic period), rabbis have known that these few pages were late additions to the Talmud, from a period they labeled “the savoraic period.” There is little historical information about this period.
The Talmud asks why our mishnah uses the language of “acquisition” whereas other mishnayot use the language of “betrothal (mekadesh)” In other words, why not teach here “a woman is betrothed?”
The word “acquisition” is used because the law that betrothal can be effected with money is derived from the use of the word “taking” in two contexts—betrothal and the transfer of money when Abraham buys the field from Ephron. Since buying something is called an “acquisition” (two prooftexts are cited), taking a woman in betrothal is called, at least by this mishnah, “acquisition.”