Menstruation and "Family Purity" (Taharat Ha-Mishpacha)
An act of will is required to turn our thoughts back to the sacred after a bodily event has focused our attention on the very physical here-and-now.
Traditional Judaism views no part of human behavior as outside the purview of religious law. Sexual activity, so full of complex moral decisions and interactions, is certainly no exception. Like all human behaviors, one's sexual life can be lived in a holy way, and Jewish law provides instruction regarding how one can bring kedushah (holiness) into relationships.
The basic rules for tohorat ha-mishpacha, or family taharah, usually translated "ritual purity"--this term and its opposite, tum'ah will be explained below--come from three chapters of Leviticus.
In Leviticus 15:19 and 24, we are told: “If a woman has an emission, and her emission in her flesh is blood, she shall be seven days in her [menstrual] separation, and anyone who touches her shall be tamei [a bearer of tum'ah] until evening...And if any man lie with her at all and her [menstrual] separation will be upon him, he will be tamei for seven days…."
Next, Leviticus 18:19 warns: "Also you shall not approach a woman in the tum'ah of her [menstrual] separation, to uncover her nakedness."
Finally, Leviticus 20:18 states: "And if a man lie with a menstruating woman and reveal her nakedness, and she revealed the fountain of her blood, both of them will be cut off from among their people."
The first of these passages is a list of that which makes one ritually tamei, the second and third a list of forbidden sexual unions. The first takes a much less stringent view of sexual relations during the week after the onset of menstruation. Quite likely this is because this list is part of a longer enumeration of bodily emissions of both men and women which render one tamei.
For both men and women, there are normal and abnormal emissions, and for both men and women, one renders oneself again tahor (non-tamei) after some time has elapsed, by immersing in the mikveh. It is only when we find the topic of menstruation embedded in the list of sexual improprieties that it takes on the additional force of a punishable offense. Note that the punishment of being "cut off" in the third passage is applicable only upon actually having sexual relations.
There is also a special case in biblical culture for a woman’s separation from others that occurs after giving birth: for a daughter, the mother is separated from others for fourteen days, and then is fully t'horah (in a state of tohorah) after sixty-six days, and she may then bring a sacrifice to the Temple. For a son, she is separated for seven days, and then waits thirty-three days. One suggestion that has been made for the doubled time for a daughter is that the daughter herself bears a "fountain of blood" and so the additional separation period reflects the presence of the daughter's body.