Free The Genesis of Justice by Alan M. Dershowitz

live or die. God had cautioned him to rule over his demons,
     but Cain succumbed to sin and murdered his brother. Rashi interprets God’s reference to “the entrance” as meaning “the entrance
     of your grave.” Yet he does not ask why God spared Cain the punishment of death. Rashi does raise the intriguing question
     of why Cain was afraid of being slain, since there were not yet people in the world, other than Adam and Eve—and he certainly
     did not fear that his own mother and father would kill him. This raises the even larger question concerning the absence of other
     people who would make procreation possible. The Bible says, “And Cain knew his wife, and she conceived.” Most of the traditional
     commentators simply avoid this inconvenient question, as I painfully learned in my days at the yeshiva. This has led skeptics—such
     as the lawyer Clarence Darrow in the famous Scopes “monkey” trial—to mock the Bible for its inconsistency. I remember feeling
     somewhat vindicated when I saw the play
Inherit the Wind
and watched Clarence Darrow cross-examine William Jennings Bryan about “where Cain got his wife.” 9 Some traditional commentators note that the text of the Bible does not purport to render a complete history; the oral tradition
     amplifies the text and provides answers to such questions.
    We are still left wondering why God is so soft on Cain’s murder of Abel. Does He not value human life more than the fruit
     of a tree—or even compliance with His unexplained prohibitions? This seems unlikely, since biblical and midrashic tradition
     tend to value human life greatly, recognizing that when a person, especially one still capable of having children, is killed,
     so too are all of his or her potential descendants. According to a midrash, God says to Cain, “The voice of thy brother’s
     blood … cries out …, and likewise the blood of all the pious who might have sprung from the loins of Abel.” 10 The talmudic principle “He who kills a single human being, it is as if he has destroyed the entire world” grows directly
     out of the Cain and Abel narrative. 11 Those who engage in genocide do so with the goal of preventing future generations. It is impossible to comprehend what was
     lost in the Holocaust or any other mass murder—how many of those killed might have saved the lives of countless others by,
     for example, discovering cures for diseases? Even the cost of one killing is incalculable.
    One resolution of the apparent conflict between God’s soft punishment of Cain and the Bible’s high regard for life is the
     possibility that the murder by Cain of Abel was the punishment inflicted
on
Adam and Eve for their sin. For a parent, there is no greater tragedy than having one child murder another. An intriguing
     midrash elaborates on the impact of the son’s actions on their parents. The text says that Cain “rose up” (
va’yyakom
) against Abel, thus implying that Cain “lay beneath” Abel and was forced to defend himself against his stronger brother.
     A midrash infers that the brothers were engaged in a “legal argument” and that Cain saved himself from Abel’s anger by importuning
     his brother to spare him on account of their parents: “We two only are in the world: what will you go and tell our father
     [if you kill me]?” Abel was “filled with pity” and let him go, whereupon the ungrateful Cain “rose up and killed” Abel. Rabbi
     Yochanan derives from this midrash the proverb: “Do not do good to an evil man, then evil will not befall you.” 12
    Some commentators expressed concern that Cain’s lenient punishment would fail to deter potential killers from acting on their
     own evil impulses, especially since Cain eventually becomes “the builder of a city.” Crime seems to pay in the early biblical
     world. Consequently some commentators saw the need to create fantastic midrashim describing the horrible, if delayed, punishment
     visited upon Cain and