6. This law, then, which the Puritan reads out of the book of nature, must, on his own admission, be a natural law, obligatory on all mankind, whether they know it or not. "The voice of nature," he says, "teaches that such marriages are now to be reprobated." Yes, and we have seen that the voice of nature was heard in ancient times, and that they were reprobated not only by the writings of their philosophers, but by the laws of nations.
But the Puritan will perhaps say, I was speaking of "the marriage of one's own sister." Be it so; and does not "the voice of nature teach" that the marriage of a man with his mother, or with his aunt, or with his son's daughter, or with his daughter's daughter, is now to be reprobated; and that there are reasons why such marriages should be forbidden by the laws of the land, "on grounds of high expediency?" Assisted by "the light of inspiration," can you find any difficulty in reading out of the book of nature a law against such marriages? Are not these marriages part of one law, recorded in Leviticus 18: vs. 6–17? and