Massekhet Nidda is the only tractate in Seder Teharot (the Order of Mishna focusing on ritual purity) for which there is a tractate of Gemara. It is easy to understand why so little Gemara exists in Seder Ṭeharot, given that the concepts related to ritual purity have become distant and theoretical since the destruction of the Temple. It is true that Seder Kodashim, which dealt with the Temple service, did continue to be discussed, and we find that the Babylonian Talmud covers most of the tractates in that Order, nevertheless there are significant differences between the two. Whereas discussing the Temple and its service indicates optimistic faith in the rebuilding of the Temple, focusing on ritual purity laws – effectively on ritual defilement – is not an expression of that dream.
Massekhet Nidda is an exception to this rule because there are two different aspects of these laws. On the one hand, the laws of nidda relate to ritual defilement; a woman who is a nidda (a menstruating woman) disqualifies sanctified objects or other things that must retain ritual purity (see 15:19-24). On the other hand, the laws of nidda forbid sexual relations between husband and wife and are included in the list of forbidden relations, together with incestuous and adulterous relationships (see Chapter 18). Although the aspect of ritual purity does not apply in modern times, the prohibition remains in place, and it is therefore essential that the laws of nidda are discussed and clarified.
Aside from the laws relating to a nidda, Massekhet Nidda deals with a number of other laws that are related in an associative manner, even though the rules are not identical. The laws most closely related to nidda are the laws of ziva (see Vayikra 15:25-30). While a male zav is someone who is suffering from a venereal disease, a woman is deemed a zava when she secrets vaginal blood outside of the time of her usual menstrual cycle. From the perspective of ritual purity, the status of a zava is more severe than that of a nidda inasmuch as the length of time that the zava must wait to become ritually pure is longer and she must also bring sacrifices to conclude the purification process.
Another type of blood that renders a woman ritually impure is dam yoledet – when a woman gives birth. According to the Torah (Vayikra 12:1-8), after childbirth a woman is considered to be ritually impure for a certain length of time (which differs depending on the sex of the child), after which time continued bleeding is considered dam tohar – blood that does not cause defilement. In this case, as well, once the woman completes the purification process she must bring sacrifices that will allow her to enter the Temple.
Aside from these vaginal blood secretions that bring about ritual impurity, there are other types of blood that are not significant from the perspective of ritual purity, at least on a Biblical level. They include blood from an ordinary wound in the vaginal wall or when the hymen is broken. According to the Torah such bleeding is entirely pure, but it is very difficult for us to know what type of blood we are looking at in any given case (see 17:8).
One topic discussed in this tractate that has wide practical applications are ketamim – blood stains. In most cases, judgment will not be made on the actual blood itself, rather on a spot of blood that has been absorbed on fabric or some other place. Often, the source of the blood is unambiguous and we are able to ascertain easily when the bleeding began, facts that allow us to reach clear rulings regarding the woman’s status.
There are cases, however, where a spot of blood is found on clothing or on the woman’s body and it is difficult to determine when the blood is from and what its source might be. Massekhet Nidda deals with these issues, mainly from the perspective of contemporary law, that is, when sexual relations would be permitted or forbidden, but also with regard to theoretical issues, like the laws of ritual purity.
There is one law that appears in this tractate that changes – and almost negates – a large part of the basic rules of the laws of nidda. The Gemara describes a rule as having been “established by the daughters of Israel,” who accepted upon themselves to view any appearance of blood – even a tiny amount – as an indication of nidda. This tradition, which was approved by the Sages, applies even in situations where there is no basis for such an assumption. Because of this stringency, many of the discussions in Massekhet Nidda have no practical application in our times.
Massekhet Nidda is considered to be one of the most difficult tractates in the Talmud. A number of reasons are offered for this:
- Many of the laws discussed in this tractate relate to ritual purity and defilement, which were viewed as being difficult to understand even when they were still applied in a practical manner.
- Laws of ritual purity have their own internal logic, which is not commonly studied since many of these laws no longer have practical application in our day-and-age.
- The Gemara avoids vulgar terminology, choosing language that avoids any expressions that might be perceived as offensive. For this reason, in many cases it is difficult for the student to be certain as to the intention of the Sages.