Commentary on Harmony of the Law Volume 2 Complete John Calvin
JOHN CALVIN
18. Neither shalt thou take a wife to her sister, to vex her, to uncover her nakedness, besides the other in her life-time
18. Mulierem quoque cum sorore sua non accipies ad affligendum et revelandum turpitudinem ejus contra eam (vel, super eam) in vita sua.
1. And the Lord spoke unto Moses. I have not introduced this declaration amongst other similar ones, which had for their object the preparation of their minds for the reverent reception of the Law, because, whatever conformity there may be in the words themselves, in their substance there is a great difference; for they were general, whereas this is specially confined to a single point. For it was not God's intention here merely to exhort the people to the study of the Law, but the address respecting the keeping of His statutes is directed to the present cause, since He does not refer indifferently to all the statutes of Himself and of the Gentiles, but restricts Himself to the subject-matter, as it is called; and thus, by the statutes of the Gentiles, He means those corruptions whereby they had perverted His pure institution as to holy matrimony. First, however, tie forbids them from following the customs of the Egyptians, and then includes all the Canaanitish nations. For, since all the Orientals are libidinous, they never had any scruple in polluting themselves by incestuous marriages; whilst it is abundantly proved by history, how great were the excesses of the Egyptians 86 in this respect. A brother had no abhorrence against marrying his uterine sister, nor a paternal or maternal uncle his niece; in a word, they were so dead to. shame that they were carried away by their lusts to trample upon all the laws of nature. This is the reason why God here enumerates the kinds of incest of which the mention would else have been superfluous.
4. Ye shall therefore keep my statutes and my judgments. Because it is no less difficult to correct vices, to which men have been long accustomed, than to cure diseases of long standing, especially because people in general so pertinaciously cleave to bad examples, God adduces His statutes, in order to recall the people from the errors of their evil habits into the right way. For nothing is more absurd than for us to fix our minds on the actions of men, and not on God's word, in which is to be found the rule of a holy life. It is, therefore, just as if God would overthrow whatever had been received
"A very objectionable custom, which is not only noticed by Diodorus, but is fully authenticated by the sculptures both of Upper and Lower Egypt, existed among them from the earliest times, the origin and policy of which it is not easy to explain — the marriage of brother and sister, which Diodorus supposes to have been owing to, and sanctioned by, that of His and Osiris; but as this was purely an allegorical fable, and these ideal personages never lived on earth, his conjecture is of little weight; nor does any ancient writer offer a satisfactory explanation of so strange a custom." — Wilkinson's Popular Account of the Ancient Egyptians, 2:224.