ancient, inherited wisdom was a natural one for Moses Sofer to make in defense of the Jewish custom of burial on the day of death.(For a full discussion of this responsum, see Treasury of Responsa, p. 236 ff.)
All this, of course, deals merely with fixing the moment of death. But the law is concerned, also, with an earlier situation, namely, the state of such people who are so badly injured or so sick as to be definitely in a dying condition with no probability of long survival. In other words, there is a great deal of debate as to when a person, although living, no longer has real viability. Such a person is called terefah by analogy with an animal which is torn by beasts and thus called terefah. Which injuries in an animal make it virtually a dying animal and therefore prohibited for food? The main injuries and ailments are considered traditional from Moses from Mount Sinai(Hulin 43a top). Maimonides elaborates the list of traditional evidences of moribundity to an enumeration of seventy such ailments(Hil. Shehitah X, 9). Do such injuries apply to human beings also? In other words, if a person has such an injury or ailment is he considered to be already in dying condition? There is disagreement in the law among the scholars as to whether that is s0. A convenient summary of the differing opinions of the Tosafists on this question is to be found in the commentary of Yom Tov Lipmann Heller , to Yevamot XVI, 4. In general, they may disagree about certain animal ailments or injuries, whether they are a mark of moribundity when found in man, but by and large they accept the standards set down for animals, namely, that if a person(as is in the case with animals) cannot be expected to live more than twelve months, such a person is considered to be in a dying condition.
These discussions of whether a person is to be considered terefah, i.e., moribund, have bearing on practical legal questions. Chaim Alfandari, in his Responsa, Magid Mereshit,#2, presents an interesting question involved here. A man may not marry his wife’s sister if his wife is still alive, but after she dies there is no such prohibition. The question asked here was the following: A man’s wife was moribund and he gave qidushin to his wife’s sister. Are these gidushin valid on the ground that
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