Whether the degrees of affinity extend in the same way as the degrees of consanguinity?

❌ Objection 1 : It would seem that the degrees of affinity do not extend in the same way as the degrees of consanguinity. For the tie of affinity is less strong than the tie of consanguinity, since affinity arises from consanguinity in diversity of species, as from an equivocal cause. Now the stronger the tie the longer it lasts. Therefore the tie of affinity does not last to the same number of degrees as consanguinity.

❌ Objection 2 : Further, human law should imitate Divine law. Now according to the Divine law certain degrees of consanguinity were forbidden, in which degrees affinity was not an impediment to marriage: as instanced in a brother's wife whom a man could marry although he could not marry her sister. Therefore now too the prohibition of affinity and consanguinity should not extend to the same degrees.