Srila Prabhupada, Los Angeles, June 14, 1972: But you must know the art. It is the arrangement of God that cow’s milk… Cow’s own milk, she does not drink. She eats grass. That means God’s arrangement is like that, that “Let the human being drink the milk of cow, and the cow may eat grass.”
Because they haven’t got good brain… Foodstuffs should be given, nice foodstuff given, should be given to the particular person for developing nice brain. Milk is a foodstuff which can develop your finer tissues of the brain so that you can understand higher philosophy.
And if you become blunt, and you eat meat by killing any animal, then how you will understand? The finer tissues given in the human form of life for understanding spiritual things… You cannot. Vina pasughnat. Therefore Pariksit Maharaja says, vina pasughnat.
Nivrtta-tarsair upagiyamanad bhavausadhac chrotra-mano-’bhiramat uttamasloka-gunanuvadat [SB 10.1.4]. Uttamasloka, Krishna, gunanuvadat, glorifying His activities, who can be bereft of this opportunity, vina pasughnat, unless he is an animal killer? Unless he is animal killer, nobody will deny to hear about Krishna.
Because the animal killers, they have lost their brain. But Caitanya Mahaprabhu’s mercy is so great that even who has lost his brain, he can be revived by hearing Hare Krishna mantra. That is Caitanya Mahaprabhu’s… Ceto-darpana-marjanam [Cc. Antya 20.12]. Yes, in this age everyone is fallen.
But he can be, I mean to say, elevated to the position of nice brain. How? By param vijayate sri-krsna-sankirtanam. Simply by chanting. So in this age everyone is blunt- headed, animal-killer. Full Lecture