Sacrifice is of human origins. God neither commands nor requests it; we have reason to suspect – and will soon be given ample evidence to defend this suspicion – that the human impulse to sacrifice is, to say the least, highly problematic, and especially from God’s point of view. To be sure, God will eventually command sacrifices, though then only under the strictest rules. As in so many other matters, the problematic is permitted but only if regulated. Because He will not, or cannot, extirpate the dangerous impulses in men, God makes concessions to them, while at the same time containing them under explicit and precise commandments.
Leon Kass – The Beginning of Wisdom p.133