Who knows one hundred fifty-eight?
Please cite/link your sources, if possible. At some point at least twenty-four hours from now, I will:
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Accept the best answer.
Go on to the next number.
Maharal writes (Gur Aryeh to Gen. 26:34) that the average human lifespan in Yitzchak's times was 158 years. (He arrives at this figure by averaging Yishmael's age of 137 years and Yitzchak's of 180.)
Thus, he continues, Yitzchak married at age 40, when he had reached one-quarter of his life expectancy; similarly, the Mishnah says that "eighteen is the age of marriage" since the average person lives to seventy, and 18 is about a quarter of that.
According to Harry Gersh, who I have no reason to think is correct, there are 158 tanaim mentioned in the Mishna.
(The user "Alex" has mentioned in a comment that this number is different from that given by the Rambam in his introduction to the mishna.)