By nature’s law, or the arrangement of the Supreme Personality of Godhead, one kind of living entity is eatable by other living entities. As mentioned herein, dvi-padāṁ ca catuṣ-padaḥ: the four-legged animals (catuṣ-padaḥ), as well as food grains, are eatables for human beings (dvi-padām). These four-legged animals are those such as deer and goats, not cows, which are meant to be protected. Generally the men of the higher classes of society—the brāhmaṇas, kṣatriyas and vaiśyas—do not eat meat. Sometimes kṣatriyas go to the forest to kill animals like deer because they have to learn the art of killing, and sometimes they eat the animals also. Śūdras, too, eat animals such as goats. Cows, however, are never meant to be killed or eaten by human beings. In every śāstra, cow killing is vehemently condemned. Indeed, one who kills a cow must suffer for as many years as there are hairs on the body of a cow. Manu-saṁhitā says, pravṛttir eṣā bhūtānāṁ nivṛttis tu mahā-phalā: we have many tendencies in this material world, but in human life one is meant to learn how to curb those tendencies. Those who desire to eat meat may satisfy the demands of their tongues by eating lower animals, but they should never kill cows, who are actually accepted as the mothers of human society because they supply milk. The śāstra especially recommends, kṛṣi-go-rakṣya: the vaiśya section of humanity should arrange for the food of the entire society through agricultural activities and should give full protection to the cows, which are the most useful animals because they supply milk to human society.