(Prabhupada's lecture - Śrīmad-Bhāgavatam 1.16.13-15 - Los Angeles, January 10, 1974)
People are searching after knowledge, philosophers, scientists, politicians, and others, so many. Everyone is after knowledge. Brahma-jijñāsā. Jijñāsā, everyone is inquiring what is the Supreme Absolute Truth. That is possible in this human form of life, not in the cat's and dog's life. So those who are cats and dogs in the form of human being, they cannot inquire. They cannot inquire. Because they may be in the form of a human being, but actually they are no better than cats and dogs. Who are they? So āhāra-nidrā-bhaya-maithunaṁ ca sāmānyam etat paśubhir narāṇām. Then the eating, material necessities of life... Eating. We want to eat something. We must eat, to keep this body fit. Then we must sleep also after eating. Not always. Not in this assembly, but after eating, you can sleep. (laughter) There is sleeping place, but not here. That is not good. So eating, sleeping. Then, after eating, after sleeping, everyone knows—the sex becomes agitated. Then mating. Eating, sleeping, mating, and defending, "How to protect myself?" Because the whole world is full of enemies. This is material world. So everyone is struggling hard, "How to protect myself?"
So these four principles are animal principles. So that is the difference, that such animal propensities are there amongst the cats and dog, and in the human being also, these necessities are there. But if we remain captivated only by these four principles, then we remain cats and dog. It doesn't matter, however nicely we are dressed, but we remain as cats and dog, in the category of cats and dog. The modern civilization is that he is actually a dog, a cat, but he dresses himself very nicely, to become gentleman. So śāstra says, no. We have to test whether he is human being or a cat and dog, what he is. So if we see that people are engaged only in these four business—eating, sleeping, mating and defending—he is cat and dog.
Above them, they are inquiring. Athāto brahma jijñāsā. They are inquiring about the Absolute Truth. They are above these cats and dogs. This is the test, what subject matter he is inquiring. Just like there are big, big scientists. They are making research, "If petrol can be substituted?" So in the eyes of the common man he may become a very great scientist, but those who are advanced in spiritual consciousness, they will take him no better than cat and dog—because his subject matter is how to eat, sleep or mate or defend. The subject matter... We have to understand what is the subject matter of this person. In the English proverb it is said, "A man is known by his company." So similarly, if the subject matter is animalistic, āhāra-nidrā-bhaya-maithuna, then, however he may be big man, we will take him amongst the categories of cats and dogs.