228. Whether, therefore, Cain was killed or not, I cannot with any certainty say, for the Scriptures afford no plain information upon that point. This one thing, however, evidently can be proved from the present text, that Cain had no certain promise of the preservation of his life; but God left him to a life of uncertainty, doubt and restless wandering, and did no more than protect the life of Cain by a command and a threat which might restrain the wicked from killing him, on account of the certain awful punishment which would follow such destruction of the murderer. But a promise that he should not be murdered was withheld. We know, moreover, what is the nature of the law, or a legal command, and that there are always very few who obey it. Therefore, although it is not recorded at what time, in what place, or by whom, Cain was slain, yet it is most probable that he was killed. The Scriptures however make no mention of it, even as they are quite silent also concerning the number of the years of Cain, and say nothing about the day of his birth or the day of his death. He perished, together with his whole generation; to use a popular proverb, "without cross, candle, or God." A few only of his generation are excepted, who were saved by the uncovenanted mercy of God.
229. The question is here usually asked, To what persons could the words of Cain possibly apply, when he says, "Everyone that findeth me shall slay me," when it is evident that besides Adam and Eve and their few daughters, no human beings were in existence. I would at once reply that they bear witness to the fact that we see the wicked "flee when no man pursueth," as the Scriptures say; for they imagine to themselves various perils where none really exist. Just so we see it to be the case with murderers at the present day, who are filled with fears where all is safe, who can remain quiet nowhere, and who imagine death to be present everywhere.
230. However, when it follows in the command of God, "Yea, verily, whosoever slayeth Cain shall be punished sevenfold," these words cannot be referred exclusively to the fears of Cain, for Cain had sisters, and perhaps he greatly dreaded that sister whom he had married, lest she should take vengeance on him for the murder of her brother. Moreover, Cain had perhaps a vague apprehension of a long life, and he saw that many more sons might be born of Adam. He feared, therefore, the whole posterity to Adam. And it greatly increased these fears that God had left him nothing more than his stray mercy. I do not think that Cain feared the beasts at all, or dreaded being slain by them; for what had the sevenfold vengeance threatened upon murderers to do with beasts?
V. 15b. And Jehovah appointed a sign for (set a mark upon) Cain, lest any finding him should smite him (slay him).
231. What this mark was is not to be found in the Holy Scriptures. Therefore commentators have entertained various opinions. Nearly all, however, have come to this one conclusion—they have inferred that there was apparent in Cain a great tremor of his head and of all his limbs. They suppose that, as a physical cause of his trembling, God had changed, or disarranged, or mutilated some particular organ in his body, but left the body whole as it was first created, merely adding a visible outward mark, such as the trembling. This conjecture of the fathers contains much probability, but it cannot be proved by any testimony of the Scriptures. The mark might have been of another kind. For instance, we observe in nearly all murderers an immediate change in the eyes. The eyes wear an appearance of sullen ferocity, and lose that softness and innocence peculiar to them by nature.
232. But whatever this mark was, it was certainly a most horrible punishment; for Cain was compelled to bear it during his whole life as God's penalty for the awful murder which he had committed. Rendered conspicuous by this degrading mark, hateful and abominable in the eyes of all, Cain was sent away—banished from his home by his parents. And although the life he asked of God was granted him, yet it was a life of ignominy, branded with an infamous mark of homicide; not only that he himself might be perpetually reminded of the sin he had committed, to his own confusion, but also that others might be deterred from the crime of committing murder. Nor could this mark be effaced by repentance. Cain was compelled to bear about this sign of the wrath of God upon him as a punishment in addition to his banishment, the curse, and all the other penalties.