Akiva replied that one does not have an obligation to ensure that there exist men unclean because of a genital discharges. Rabbi Eleazar ben Hisma taught that even the apparently arcane laws of bird offerings in and menstrual cycles in and are essential laws. Tractate Niddah in the Mishnah, Tosefta, Jerusalem Talmud, and Babylonian Talmud interpreted the laws of menstruation in Rabbi Meir taught that the Torah ordained that menstruation should separate a wife from her husband for seven days, because if the husband were in constant contact with his wife, the husband might become disenchanted with her. The Torah, therefore, ordained that a wife might be unclean for seven days (and therefore forbidden to her husband for marital relations) so that she should become as desirable to her husband as when she first entered the bridal chamber. The Mishnah taught that all women are presumed clean for their husbands (and for the purpose of marital relations, no examination is required). The Mishnah taught that it is also true for men who return from a journey that their wives are presumed clean. Interpreting the beginning of menstrual cycles, as in the Mishnah ruled that if a woman loses track of her menstrual cycle, there is no return to the beginning of the niddah count in fewer than seven, nor more than seventeen days.</ref> The Mishnah taught that a woman may attribute a bloodstain to any external cause to which she can possibly attribute it and thus regard herself as clean. If, for instance, she had killed an animal, she was handling bloodstains, she had sat beside those who handled bloodstains, or she had killed a louse, she may attribute the stain to those external causes. The Mishnah related that a woman once came to Rabbi Akiva and told him that she had observed a bloodstain. He asked her whether she perhaps had a wound. She replied that she had a wound, but it had healed. He asked whether it was possible that it could open again and bleed. She answered in the affirmative, and Rabbi Akiva declared her clean. Observing that his disciples looked at each other in astonishment, he told them that the Sages did not lay down the rule for bloodstains to create a strict result but rather to produce a lenient result, for says, "If a woman has an issue, and her issue in her flesh is