Cain’s previous question – i.e. Am I my brother’s keeper? – is now followed by a further question of God. It gives voice to the indignation not only of what Cain did, but also of the total disaffection of Cain for his brother. God’s can see everything, because he is the Lord of Life, and life belongs to him. No man has the right to suppress life, without this act being unpunished. Homicide can remain unpunished in front of a human court, but not in front of God. It doesn’t exist any corrupt judicial system, any amount of money able to cover the vox oppressorum, the innocent blood who cries from the ground. Historically, the author here makes allusion – through the verb tsa’aq to shout – to the legal protection right well present in the Old Testament (see Gen 18:20; Dt 22.24; 2 Re 8:3; Gb 16:18 ff.).
The text highlights the preciousness and indestructibility of human life. It can never be totally suppressed, because a suppressed life claim the attention of God. This is so because blood – which according to Jews is the life itself – is what binds us to God. Nowadays blood can also be called soul, i.e. what characterizes us in the deep. Nothing of man is destroyed – like anything else – but in man there is something more that is not corruptible.
Blood is the symbol of every human oppression, whose cry comes – according to the Bible (see e.g. Es 1-2) – always to God, who intervenes, although in ways and forms very different from what we expect. But there is no need to resort to God. For an intrinsic law of nature if you act violently you have to expect the same act. Because nothing of what we do is disunited with what surrounds us, with others and even with God.