"One who takes to Krsna consciousness seriously and perfectly, he must be very, very intelligent." Dull brain cannot accept it. Bahunam janmanam ante jnanavan mam prapadyate [Bg. 7.19]. So we have to make our brain very clean. And for that purpose you require to drink not very much — at least one pound or half-pound milk daily. That is essential. But no meat-eating. This is intelligence. The milk is also conversion of the blood, everyone knows. Just like we drink the milk of our mother. The color of the milk is white, but everyone knows that milk is produced from the red blood, red corpuscle. So this is the process, that people are very much anxious to drink the blood of cows from the slaughterhouse. They sometimes drink fresh blood, is it not?

That is not very good intelligence. You drink the blood of the cow by natural process, which turns into white milk. You'll get better brain, better strength. Therefore cow protection is very essential in Vedic civilization. Therefore we offer respect Krsna: "Krsna is the benefactor of cows and the brahmanas." Namo brahmanya-devaya go-brahmana-hitaya ca. Go-brahmana-hitaya ca. Krsna is well-wisher first, go, cows. You'll find Krsna always with cows. Here is Krsna's picture, you see how He's loving the cow and the calf. He's personally teaching from His childhood, from His boyhood. So we should follow. If we want to become Krsna conscious, we must give… The calf is also seeing to the face of Krsna for protection, and Krsna is giving protection, "Yes, I'll give you protection."

From Srila Prabhupada's lecture on Srimad-Bhagavatam 1.16.19 — January 15, 1974, Honolulu