Halakha Mazmur 116:6: Gray Matter III & Chayyei Adam

Into which of these two categories should we place smoking? One way to distinguish between the two categories is the litmus test suggested by the Gemara in a number of places (Shabbat 129b, Yevamot 12b, and Niddah 31b). The Gemara permits certain activities that involve some risk, positing that “Since the multitudes have trodden upon this matter, [the pasuk] ‘Hashem protects the foolish’ (Tehillim 116:6) [applies].” This Gemara teaches that Halachah has allowed reasonable members of society to define the parameters of the prohibition to engage in risky activities; Halachah permits activities that such people judge to involve a tolerable risk. Based on this standard, Teshuvot Chelkat Yaakov (3:11) writes that it is permissible to travel in an airplane or car even though there is some risk involved.⁶For further explanation of the concept of Hashem protecting the foolish, see Rav Shlomo Cohen-Duras’s discussion of hazardous sporting activities (Techumin 22:120-126) and our chapters about hazardous medical procedures and cosmetic surgery.

The custom is not to perform bloodletting on the eve of any festival, for on Erev Shavuot, a demon named Tavuach goes forth, and had Israel not accepted the Torah, he would have slaughtered them for their flesh and their blood. The Rabbis therefore decreed [the prohibition] for all festival eves on account of Erev Shavuot. As for cupping glasses, called bankes or Köpfsetzen, some authorities permit them, except on Hoshana Rabbah, which is a Day of Judgment. In any case, on Erev Shavuot one should be stringent. On the night before a festival, bloodletting is permitted, except for the night of Hoshana Rabbah. The last day of Passover is entirely permitted, as it is not a festival unto itself. (Magen Avraham, Siman 468) All of the above applies when one wishes to let blood for purposes of health. However, where there is danger to life, the matter has already been widely trodden upon, and "God protects the simple" (Psalms 116:6). Even on Erev Shavuot, the Be'er Heitev permitted it when physicians ordered bloodletting in an illness involving mortal danger — for one can say it is specifically their [ancient] form of bloodletting that was prohibited, but not our [modern] form. Therefore, in a case of danger, one should permit it but not otherwise.