In relationship by marriage, the principal point of interest is the degrees of relationship within which marriage was forbidden. Thus a woman must not marry two brothers, unless her husband had died without issue, when the brother was required to raise up seed to the deceased. Apparently a man might by the law of Moses marry his deceased wife's sister; but not the second in the life-time of the first, Leviticus 18:18 , though Jacob before the Law was given had two sisters for wives at the same time. Near relatives may not marry: cf. Leviticus 18 . Many codes respecting the degrees of affinity have been made by nations, more or less in agreement with the law of Moses. See MARRIAGE.