Then Moses called for all the elders of Israel, and said unto them, Draw out and take you a lamb according to your families, and kill the passover.
All Commentaries on Exodus 12:21 Go To Exodus 12
What then did Moses do? “Sacrifice an unblemished lamb,” he said, “and smear your doors with its blood.” What do you mean? Can the blood of an irrational animal save one who expresses reason? “Yes,” he says. “Not because it is blood but because it prefigures the Master’s blood.” Although statues of the emperor have neither life nor perception, they can save the men endowed with perception and life who flee to them for refuge, not because they are bronze but because they are images of the emperor. So too that blood which lacked life and perception saved the men who had life, not because it was blood but because it was an anticipatory type of the Master’s blood.