Reb Yochanan would sit by the mikveh so that later on, the women would think of him. Another Gemorah (Nedorim 20b) which is codified by the Rambam and Shulchan Oruch says that one should not be thinking of another woman during tashmish, and doing so may lead to bad children.
Is it osur only for the man to think of another, but OK for a woman? Why couldn't a man think of a tzadekes just as a woman could think of Reb Yochanan?
Mark Kohn, Los Angeles, Ca USA
A fine question!
As you point out, the Gemara in Nedarim speaks specifically about a man and not about a woman. Maybe that is because men tend to think about women differently than women think about men.
I doubt whether a man thinking about a Tzadekes would work anyway, as Tzidkus depends upon a person's efforts and not upon thinking about someone else. By R. Yochanan the women would see his handsomeness, which would affect the child's beauty, not necessarily the child's Tzidkus. And besides, there are surely plenty of male Tzadikim to think about, even if there were no other people as handsome looking as R. Yochanan.
R. Eliezer Chrysler