Do Not Have Relations with One's Mother
The Opening of the Incest Code — What the Forbidden Relationships Define
Leviticus 18:5: “You shall therefore keep my statutes and my rules; if a person does them, he shall live by them: I am the LORD.” The incest code of Leviticus 18 opens with a framing statement — life comes from keeping these statutes — and then lists the forbidden relationships. Leviticus 18:6: “None of you shall approach any one of his close relatives to uncover nakedness. I am the LORD.” The general prohibition on approaching close relatives is then elaborated through a list of specific relationships. The mother-son prohibition (Leviticus 18:7) is the first and most foundational on the list: the relationship that most obviously defines the category of “close relative.”
The phrase “uncover nakedness” (galeh ervah) is the Torah’s euphemism throughout this passage for sexual relations. The mother is the paradigmatic case: all other incest prohibitions are extensions and specifications of the same core concept — the closest family relationships must not become sexual relationships. The mother-son prohibition is listed first because it is the most self-evident, the most universally recognized, and the prohibition from which all others derive their moral force.
Double Prohibition — Father’s Honor and Mother’s Identity
Leviticus 18:7: “Do not dishonor your father by having sexual relations with your mother. She is your mother; do not have relations with her.” The verse contains two clauses. The first frames the prohibition as a violation of the father: “the nakedness of your father” — relations with the mother dishonor the father whose intimate domain she is. The second clause grounds the prohibition in the mother’s own identity: “she is your mother.” The redundancy (why state it twice?) is legally significant in rabbinic reading: two clauses yield two prohibitions. One covers the biological mother; the other covers the father’s wife (who may be a different woman — a stepmother).
The father’s honor framing connects this prohibition to the commandment to honor one’s father and mother (Exodus 20:12). Relations with the mother are not only a sexual violation but a violation of the fifth commandment’s spirit — the most radical form of dishonoring the father possible. The Torah’s ethics of family relationships are interconnected: the incest code and the honor commandment address the same relational structure from different angles. The family that honors parents correctly also does not violate the sexual boundaries that the honor structure requires.
Egypt and Canaan — What Israel Must Not Become
Leviticus 18:3: “You must not do as they do in Egypt, where you used to live, and you must not do as they do in the land of Canaan, where I am bringing you. Do not follow their practices.” The incest code opens with a double prohibition — not the practices of Egypt (where Israel was) and not the practices of Canaan (where Israel is going). The implication is that both cultures practiced some of what Leviticus 18 prohibits. The forbidden relationships are not merely personal moral violations but cultural identities: this is what Egypt does, this is what Canaan does — and Israel must be different.
Leviticus 18:24: “Do not defile yourselves in any of these ways, because this is how the nations that I am going to drive out before you became defiled.” The incest code’s prohibitions are tied to the Land’s fitness for habitation — the nations who practiced these things defiled the Land, and the Land “vomited them out” (Leviticus 18:28). The mother-son prohibition, first on the list, is thus not only a personal sexual ethic but a foundational requirement for covenant life in the Land. A people that maintains these boundaries remains fit for the Land; a people that violates them follows the nations who were expelled.
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