Once a month, after nightfall, my wife keeps a secret appointment. Neither our neighbors, our friends, nor our children know where she goes, although our children sometimes wonder why she returns an hour or so later with her hair wet… …Once a month, my wife goes to the mikvah. In this way, she and I observe one of the most ancient… traditions in Judaism. For a week and a half before mikvah night, we avoid marital relations. We can relate as friends, partners and confidants, but not as lovers. On mikvah night we come back together as sexual partners. My wife and I are not Orthodox Jews…..Nevertheless, in our marital life, we have chosen to observe the ancient laws of mikvah, known euphemistically as Taharat Hamishpacha, "Family Purity"… My wife and I have found a number of reasons for observing the laws of mikvah - philosophical, symbolic, feminist and traditional. These laws make a philosophical statement about sexual relations that needs to be made today. Our society wavers between ascetic and hedonistic views of sex. The ascetic view ties sex to sin and is embarrassed by sex. The hedonistic view, reacting to this, sees pleasure as the ideal, condoning any activity between consenting adults. Judaism rejects both these extremes. It teaches that sex is G-d's gift to humans and is therefore holy. Full article here.