“Before Adam sinned, what was written? God said, ‘Look, I have given you every [seed-bearing] plant…’ (Genesis 1:29), and to you it shall be for food (ibid.), but nothing more. After he sinned and the evil impulse had been absorbed into his body and that of his descendants, He executed judgment upon them.
Afterward, Noah came and perceived that the body was built upon the pervasive evil impulse. He offered a sacrifice just as Adam did. What is written? YHWH smelled the pleasing aroma… since the devisings of the human heart are evil from youth (Genesis 8:21). The blessed Holy One said, ‘From now on, since his body has been imbued with the evil impulse, let the body enjoy as much as a person sees fit—let him eat meat [cf. Deuteronomy 12:20: when your appetite craves eating meat, wherever your appetite’s craving may be, you shall eat meat].
Like the green plants, I have given all to you (ibid. 9:3). When he eats meat, his own flesh delights from that flesh, and they intermingle. His body swells as a result; and on account of the pleasure the body sins copiously. Thus, the blessed Holy One said, atonement for the body—with flesh. Meat that a person eats produces blood for the body. Blood remaining from that meat—drained—is designated for atonement for blood, manufactured from its own flesh. This is as is written: it is the blood that gains atonement through the soul (Leviticus 17:1)” (Zohar 1:89b, Sitrei Torah, cf. BT Sanhedrin 59b).
“[Suffering] came to Rabbi [Yehudah ha-Nasi] through a certain incident. What was it?—a calf was being lead to the slaughter, when it broke away, hid his head under Rabbi’s coat tails, and lowed [in terror]. ‘Go,’ he said, ‘for this were you created.’ Thereupon they said [in the heavenly court], ‘Since he has no pity, let us bring suffering upon him.’
And [suffering] departed likewise. How so?—One day Rabbi’s maid servant was sweeping the house; [seeing] some young weasels lying there, she went to sweep them away. ‘Let them be,’ he said to her; ‘It is written, His mercy is over all His works (Psalms 145:9).’ They said, ‘Since he is compassionate, let us be compassionate to him.’ Whereupon suffering departed from him (BT Bava Metsi’a 85a).
“Why did God deem it necessary for man to slaughter animals for his food? Is it not written: YHWH is good to all and His mercy is over all His works (Psalms 145:9). And if He is merciful, how could He command that animals be slaughtered for food? Where is His mercy? The essence of the verse is contained in the first clause: YHWH is good to all—absolutely good! Therefore His Mercy is over all His works.
This is the interpretation: in the Work of Creation it is predetermined if a particular animal is destined to be slaughtered, and the animal says ‘good.’ What is the reason for this? The animal does not have a נְשָׁמָה (neshamah), soul [but only a נֶפֶשׁ (nefesh), life-breath, see Genesis 1:24, cf. Leviticus 17:11], with which to grasp the deeds and might of God, and so God says to them: ‘Do you wish to be slaughtered and eaten by man and by doing so ascend from the rung of an ignorant animal to the rung of a human who knows and recognizes YHWH, may He be blessed?’ The animals answered, ‘good, and mercy will be upon us.’ For when man eats from parts of an animal that animal in turn becomes part of man’s body, so the animal turns into man and it’s slaughter is an act of mercy, for it has left the reality of the animal and entered the reality of the human.
Thus the death of the human is life for the animal, for it ascends to the heights of angels and this is the essence of the verse YHWH saves man and beast (Psalms 36:8). If this is so, understand the essence of [ritual animal] slaughter: it is done as an act of His abundant mercy and compassion upon all His creatures, thus you should contemplate what the Sages have taught in Pesaḥim: ‘An ignoramus is forbidden to eat meat [for it is said, This is the תּוֹרַת (torat), teaching, about beast and bird (Leviticus 11:46); whoever engages in Torah may eat the flesh of beast and bird, but he who does not engage in Torah may not eat the flesh of beast and bird]’ (BT Pesaḥim 49b) [cf. Sefer ha-Qanah 120r]—slaughtering animals is only a commandment for those who know what the Law says regarding domesticated animals, wild animals, and foul.
All who are involved in Torah are permitted to eat meat, and all who are not are forbidden. Therefore a man unlettered is forbidden to eat meat, for he is like a domesticated animal without a נְשָׁמָה (neshamah), soul. He is not allowed to slaughter an animal for the benefit of another animal, unless it has already become unfit for [ritual] slaughter” (Rabbi Yosef Gikatilla, Sha’arei Orah, Sha’ar ha-Shishi, Sefirah ha-Ḥamishit).
“Flesh is garment of the human, as is written everywhere: flesh of a human (Exodus 30:32)—human, within; flesh, garment of the human, it’s body.
Specters below, melted in the smelting of this spirit, were figured into figures clothed in another garment, such as figures of pure animals: ox, sheep, goat, deer, gazelle, roebuck, wild goat, ibex, antelope, and mountain sheep (Deuteronomy 14:4–5), who desire to be interwoven in the garment of the human, flesh of the human” (Zohar 1:20b).