1
Rabbi Chagai opened and said: That which is written (Numbers 28:2), "My sacrifice, My food of My fires, etc." "My sacrifice" - that is the sacrifice of the flesh that is offered to atone, blood for blood, flesh for flesh. [That is] because all sacrifices are only sacrificed for flesh to atone for flesh.
2
And this is what I heard: If a man sinned, what was the sin of the animal? It is that the Holy One, blessed be He, said (Leviticus 1:2), "If any one of you bring an offering, etc." Why? The Holy One, blessed be He made the spirit of people the spirit of animals, and separated this from that. And because of that, "it is the spirit of man that ascends on high and the spirit of the animal that [descends], etc." (Ecclesiastes 3:21). Certainly, this is separate from that.
3
Before man sinned, what is written? "Behold, I have given you all seed-bearing plant, etc." (Genesis 1:29). And it is written, "to you it shall be for food." But nothing more. Once he sinned and the evil impulse was absorbed into his body and those of all his descendants, He executed judgement upon them.
4
And then Noach came and saw that the body was built from the place of the evil impulse, he offered a sacrifice, like Adam had sacrificed. What is written? "And the Lord smelled the sweet savor, etc." (Genesis 8:21). And it is written, "for the impulse of man’s heart is evil from his youth." The Holy One, blessed be He, said, "From now on, since the body has absorbed that evil impulse, let the body enjoy as much as it sees fit, let it eat meat" - "as with the green plants, I now give you all" (Genesis 9:3).
5
When he eats meat, his flesh enjoys [the animal's] flesh, one becomes mixed with the other and his body grows from it. And due to this pleasure, the body sins several sins. The Holy One, blessed be He, said, "The atonement for the body is flesh. It ate flesh and his flesh grew from it and sinned through it. Because of that, let the flesh atone for his body!" And the flesh that he ate, [that] flesh made blood for the body. (Because of this, the blood that remained from that meat that he ate, [that] flesh made blood for the body.) Because of this, the blood that remained from that meat outside is destined for atonement for the blood that was made from that flesh from it, as it is written (Leviticus 17:11), "for it is the blood that will achieve atonement for the soul."