Prabhupada's lecture - Śrīmad-Bhāgavatam 1.3.14 - Los Angeles, September 19, 1972

These rascals, the scientists, they do not know that milk is nothing but transformation of the blood. That everyone knows. So if you want to... That is nature's way, by God's will, that a cow gives forty pounds, fifty pounds milk daily, but it does not drink. Although it is her milk, no, it gives you, human society: "You take. But don't kill me. Let me live. I am eating only grass." Just see. And the civilized men killing them, killing them. And they want peace. Just see the fun. Without touching your foodstuff, the cow is eating the grass which is given by God, immense grass, and they are giving you the finest foodstuff, milk. Just after your birth you have only to drink milk, either mother's milk...

Nowadays, mothers do not supply milk. That is also to be supplied by the cow. So from the very beginning of my life I am subsisting by the foodstuff given by mother, cow, and when I am grown up, I kill. This is my gratitude. Just see. And they are called civilized. Less than lowest animal, narādhama. They are called narādhama, lowest of the mankind. Those who are killing cows, maintaining slaughterhouse, they are lowest of the mankind. They are not human being. Less than animal. They have no gratitude.