The human race, however, is inclined to judge sins, not according to the gravity of the evil desire involved, but rather with reference to the importance attached to their own customs. So people frequently reckon that only those acts are to be blamed which in their own part of the world and their own time have been customarily treated as vicious and condemned, and only those acts to be approved of and praised which are acceptable to those among whom they live.
De Doctrine Christiana, III.10.15
Was reading this passage this evening and struck by how true it is. Apologies for the lack of interesting blog posts, hope to get some in next week.