[177] Moses says in the next passage that the Lord God set a mark upon Cain in order to prevent any one who found him from slaying him; but what this mark is, he has not shown, although he is in the habit of explaining the nature of everything by a sign, as he does in the affairs of Egypt, where God changed his rod into a serpent, and withered the hand of Moses till it became like snow, and turned the river into blood.