The classical rabbis interpreted Leviticus 18:30 to mean that they should (metaphorically) create a protective fence around the biblical laws,[42] and this was one of the three principle teachings of the Great Assembly.[43] Mixing of milk and meat is one area of halacha where a particularly large number of "fences" have been added. Nevertheless, the rabbis of the classical and Middle Ages also introduced a number of leniencies.[citation needed]