Musar su Genesi 31:35

כי דרך נשים. Nachmanides points out that in earlier days menstruating women were quarantined to the point where one did not even talk to them. The experts in those days were aware that the breath emanating from these women was harmful. Nachmanides mentions that he was going to report on scientific experiments conducted which prove such a theory. The Talmud also reports such an isolation of menstruating women. Rabbi Yochanan says that it is forbidden to walk behind such a woman, to step on the dust she walked on, and to make use of what she has handled during her period. This is why Rachel said to her father that actually she ought to be getting up and kiss his hands; she warned him not even to walk about within her tent since the dust that she had walked on might prove harmful to him. Laban remained silent and did not respond because one did not speak to women whom one knew to be menstruating. Thus far Nachmanides.