397. We have learned it is written, "Also you shall not approach to a woman in the impurity of her menstrual flow, to uncover her nakedness" (Vayikra 18:19). Rabbi Yehuda taught, the generation in which Rabbi Shimon bar Yochai dwells are all meritorious, all pious, all sin fearing, the Shechinah dwelling in their midst. Not so in other generations. For this reason, these things are expounded and not concealed, IN HIS GENERATION. In other generations it is not so, and supernal secrets cannot be revealed. And those who do know them are afraid TO REVEAL. When Rabbi Shimon would relate the secret of this verse among all the friends, their eyes would flow with tears. All the words he said were being revealed before their very eyes, as the verse says, "With him I speak mouth to mouth, manifestly, and not in dark speeches" (Bemidbar 12:8).