Prabhupāda: So one who is in the bodily concept of life, and this is how the world is working today, he is go-kharaḥ, animal. ‘go’ means cow and ‘kharaḥ’ means ass. Sa eva go-kharaḥ. So one who understands the real religious principles (dharma), just like it is said here, guhyaṁ viśuddhaṁ. Viśuddha means that it is not a material thing. The material things are all contaminated because of which it is destroyed. And viśuddha means that which is never destroyed, soul, na hanyate hanyamāne śarīre (BG 2.20), that is pure. The body is not pure. To make the body pure we have to follow real relgious principles (dharma). That is why different relgions, varnasrama-dharma is called real relgion, brahmana, ksatriya, vaisya, sudra, brahmacari, grhastha, vanaprastha, because we are all in a contaminated position, so to regulate it, to go to the purified platform we should follow these divisons. If we discard them then we remain contaminated, don’t get purified.
That is why in our Vedic civilization to follow the principles of varnasrama-dharma is the preliminary duty of human form of life. And one who does not understand varnasrama-dharma and does not strive for it, he remains contaminated. For many births he leaves one body, accepts another one, work for some time and then die and again accept another body, this cycle of birth and death, the same contaminated state.
So that is why it is said in the scriptures, tapo divyaṁ putrakā yena śuddhyed sattvaṁ (SB 5.5.1), the human life is meant for purifiying existence. It is not that sometime we get the body of a monkey, and sometime of a demigod, jump aorund for some time, then die and again get another body, this is not human life. Athāto brahma-jijñāsā (Vedānta-sūtra 1.1.1). Human life is meant for understanding the Absolute Truth. Therefore Rsabhadeva has said, when He was preaching to his sons, before retirement, He had hundred sons to whom He was preaching, Maharaja Rsabhadeva, He said this only that, son