What does it mean to say “the voice of thy brother’s blood crieth unto me from the ground” (Gen 4:10)?

While literally it suggests that the ghost of Abel was calling to God, its clear figurative, even poetic, meaning is that God is aware of the horror of a brother’s life blood covering the ground. The next verse continues the image, saying the earth “opened her mouth to receive thy brother’s blood from thy hand”. It is eloquent that God chooses to describe the first murder in such poetic terms. It is interesting that there are many references to blood being shed upon the ground in the Bible. For example, “O earth, cover not thou my blood, and let my cry have no place.” (Job 16:18) Perhaps the most striking connection, however, is in the deliberate pouring out of blood on the earth next to the altar in a blood sacrifice (e.g., Lev 4:18). This hardly suggests that Abel is a sacrifice, but he is the first martyr, as Jesus intimates and as we have already seen.