Prabhupāda: So the human life is meant for purification. Sattva-śuddhi. In the Bhagavad-gītā there is, abhayam... What is that? Can anyone... Abhayaṁ sattva-saṁśuddhiḥ. Sattva-saṁśuddhi, it is very important thing. Sattva means my existence. I am eternal. So I am existing, but I am suffering. I am suffering. Just like I have got now cold affection (infection). This is not my natural state, but I have been affected by chilly cold or something like that. Therefore I am suffering. So it is my duty to cure it, to take some medicine, to go to the physician. That is called sattva-saṁśuddhi, purifying your existence. By nature, by constitutional position, every living entity is as pure as God. But God does not become impure. We become impure. Therefore we are suffering. That is the... So this impurity can be rectified in this life, this human form of life. Therefore human form of life is meant for purification. Therefore so many scriptures are there, so many teachers are there, so many rules and regulations are there. They are not meant for the animals, because they cannot be purified. They must have to come to this position by evolution of human being. Then there is chance of purification.
Therefore in this human life, if we do not purify our existence, then we go on with this impure existence. Impure existence means transmigration of the soul from one body to another, and become subjected to birth, death, old age and disease. This is impurification. So they do not know that "Death is not my obligation. Because I am impure, therefore I am dying. Birth is not my obligation. Because I am impure, therefore I am taking birth." Janma-mṛtyu... Four things: janma-mṛtyu-jarā-vyādhi (BG 13.9). Janma, birth, is due to my impure consciousness. Therefore if we purify our consciousness by advancing, by developing Kṛṣṇa consciousness, then we become pure. This is the process of Kṛṣṇa consciousness movement. Ceto-darpaṇa-mārjanam (CC Antya 20.12), Caitanya Mahāprabhu says, cleansing the heart. And all these purificatory methods, they are based on cleansing the heart. If I think myself that "I am something of this material product..." The scientists, they say that "I am these material things." They do not understand what is spiritual identity. And I do, I act, according to that material conception, that is impurity of my consciousness. First thing is to understand that "I am not this material body."
Therefore, spiritual education begins from this body. As Kṛṣṇa says in the Bhagavad-gītā, dehino 'smin yathā dehe (BG 2.13). Asmin dehe, in this body there is the spiritual spark who is the proprietor of the body. This is the beginning of spiritual education. What is, the scientists cannot imagine, or they have no idea, from there we begin our education in spiritual life, beyond their jurisdiction, beyond the jurisdiction of the scientists. And how they can understand this movement? It is beyond their jurisdiction. When they will receive one hundred or one thousands of Nobel Prize, at that time they may be able to understand that where Kṛṣṇa consciousness movement begins. They do not know even where the Kṛṣṇa consciousness movement begins. Therefore, generally people cannot understand what is this Kṛṣṇa consciousness movement. They think it is some religious sentiment. Like so many other religions, it is like that. No. It is most the scientific movement, purifying the existence of the living being so that he can eternally, blissfully live, with complete knowledge. That is Kṛṣṇa consciousness movement. To purify. Yena śuddhyet sattvam. And for such... Just like for being cured from your attack of cold and cough, you take so many medicine, go to so many physician, you spend some money. Why? You want to be cured. Similarly, if you understand that "This is my disease, repetition of birth, death, old age and disease," so you'll have to sacrifice. Just like you are sacrificing money for being cured from the diseased condition, similarly, śāstra says that this human life is meant for tapasya, tapasya. Tapo divyaṁ yena śuddhyet sattvam (SB 5.5.1). This human life is meant for tapasya, not for indulging in sensual gratification like the animals. Tapasya. So in the tapasya method these things are prescribed. So Yudhiṣṭhira Mahārāja is mentioning them.
So this Kṛṣṇa consciousness movement means training people how to become tapasvī, tapasvī, who is undergoing tapasya, regulative, so that he may be cured from this permanent disease, birth, death, old age and disease. The Kṛṣṇa consciousness movement. The whole Vedic process is meant for that purpose, to purify the existence of the living being so that he can be saved from the repetition of birth, death, old age and disease. You read some of the purport.
Pradyumna: Aśvamedha-yajñas or gomedha-yajñas, or the sacrifices in which a horse or a bull is sacrificed, were not, of course, for the purpose of killing the animals. Lord Caitanya said that such animals sacrificed on the altar of yajña were rejuvenated and a new life was given to them. It was just to prove the efficacy of the hymns of the Vedas. By recitation of the hymns of the Vedas in the proper way, certainly the performer gets relief from the reactions of sins. But in case of such sacrifices not properly done under expert management, certainly one has to become responsible for animal sacrifice."
Prabhupāda: This is a long subject matter. But the sacrifice in yajña, recommended, that is not for killing the animal, but it is a testing, how the Vedic mantras are being properly chanted. Because an old animal put into the fire, by Vedic mantras he would come out again with young life. That is sacrifice of animals in the yajña. Therefore in this age there is no such expert brāhmaṇa who can chant the mantras properly or he can behave because the life is very abominable. Therefore, because there is no expert brāhmaṇa, so these sacrifices are forbidden in this age. Kalau pañca vivarjayet aśvamedhaṁ gavālambhaṁ devareṇa sutotpattiṁ sannyāsam (CC Adi 17.164). These things are forbidden in this age, because there is no proper men to conduct.
So in the Kali-yuga this sacrifice is recommended: yajñaiḥ saṅkīrtana-prāyair yajanti hi sumedhasaḥ (SB 11.5.32). Saṅkīrtana-yajña. This yajña will help you. Real thing is the heart, the mind. If this yajña, saṅkīrtana-yajña, cleanses your mind and heart, then you come to the platform of knowledge. Then automatically other things become effective. So in this age it is recommended that other yajñas will not be effective, neither it is recommended. But the saṅkīrtana-yajña-yajñaiḥ saṅkīrtanaiḥ—that is recommended. Everyone can join it, and he can become purified, he can become situated on spiritual platform, and his life becomes successful.