Toharot, Chapter Five, Mishnah Eight
The spit of a woman who is a menstruant is impure. Women who are menstruating are expected not to go around spitting in the public domain. Our mishnah deals with a town in which there are women who may not observe thisi.e. they go around spitting. Glad this doesn’t seem to happen as much anymore.
1) If there was in the town one who was not of sound sense, a Gentile, or a Samaritan woman, all spit encountered in the town is deemed unclean.
2) If a woman trod on a man’s clothes or sat with him in a boat:
a) If she knew that he was one who eats terumah, his clothes remain clean:
b) But if not, he must ask her.
Section one: The woman who is not of sound senses is not assumed to refrain from spitting when she is menstruating. Gentile and Samaritan women also don’t refrain from spitting because they don’t know or perhaps don’t care that their spit defiles (when menstruating). Therefore, if there is one such woman in the city, all found spit is impure.
Note that according to rabbinic understanding of the Torah, only Jews transmit impurity. However, the rabbis decreed that Gentiles too can transmit impurity. Thus a Gentile menstruant’s spit is impure. Samaritans are sometimes considered as Jews, and sometimes not. The rabbis said that a Samaritan woman is considered as a menstruant from birth. See Nidah 4:1 (we will learn this in a few months).
Section two: A zavah or a menstruant impart midras impurity by pressing on clothing. This includes sitting on something, leaning on it or standing upon something.
If a woman stepped on a man’s clothing or sat close to her on a boat, he needs to know whether she is impure if he wants to eat terumah. So if the woman knew that he ate terumah, for instance, if she knew that he was a priest, then we can assume that she would have been careful and his clothes are clean.
However, if she didn’t know him, he must ask her if she is indeed a menstruant or zavah. You can imagine that this would have been awkward. Probably not a good way to start a conversation, especially on the tight quarters of a boat.