484. (4) Triple adultery is adultery with close blood relatives. We call this triple adultery, because it is three times more grave than the previous two kinds. (For a list of the close blood relatives or near of kin which are not to be "approached," see Leviticus 18:6-17.*) Such adulteries are three times more grave than the foregoing two kinds for reasons that are internal and external. The internal reasons derive from the correspondence of such adulteries with a violation of the spiritual marriage, which is that of the Lord and the church and so then of goodness and truth. The external reasons, on the other hand, exist as matters of protection, to keep a person from becoming an animal. However, we do not have the space here to proceed to a discovery of the reasons. * These include: father, mother, stepmother, sister, stepsister, granddaughter, half sister, paternal or maternal aunt, uncle, uncle's wife, daughter-in-law, sister-in-law, stepdaughter, mother-in-law, stepgranddaughter.