In this sermon From The Rib Of Adam To The Rib Of Christ, we gain understanding behind the law of the City of Refuge.

The Seed of the woman is seen crushing the head of the serpent that seduced Adam and Eve to sin. Adam had to leave due to the serpent. So if the serpents work could be undone, man could return. And it was undone by having man, from Adam's side. Man thrown into sin... put into Christ by Christ's side being opened.