Leviticus can also be called “The Book of the Law of the Priests” as it contains very little historical matter, concerning itself with priestly legislation and the practice of the Law among the people. Much importance is placed upon Israel’s separation from all heathen influences so that the nation may retain its religious purity.

Leviticus 15

15:25 And if a woman have an issue of her blood many days out of the time of her separation, or if it run beyond the time of her separation; all the days of the issue of her uncleanness shall be as the days of her separation: she shall be unclean.