In the Vedic scriptures, Kathopaniṣad, it is said, tad-vijñānārthaṁ sa gurum eva abhigacchet (MU 1.2.12). Upaniṣad, whatever is spoken in the Upaniṣad, that is gospel truth. That is the system of understanding transcendental knowledge, veda-pramāṇa, evidence from the Vedas. According to Vedic system, amongst the learned scholars, if one presents Vedic evidences, then his position is strong. Just like in law court, two lawyers are arguing. One lawyer who quotes from the law book various bona fide quotations, the judgment is given in his favor because that is authorized.
Similarly, a Vedic statement is accepted in Indian spiritual society. There are hundreds and thousands of men who are still dedicated. Practically the whole population of India, they are dedicated to spiritual life. Perhaps you may not know, but anyone who has taken birth in India, he has got a natural inheritance of spiritual life. Unfortunately, at the present moment the leaders are under wrong impression that in India, being too much spiritually inclined, its material advancement has been checked.
But material advancement does not become hampered by spiritual knowledge. That is a wrong impression. Rather, if you become spiritually advanced, your material necessities will be very nicely adjusted. That is the injunction, Bhagavad-gītā, yuktāhāra-vihārasya yogo bhavati siddhi-hā (BG 6.17). Yoga. Spiritual life means yoga. So yogic life can be very nicely successful if you adjust your material necessities of life. If you become extravagant so far your material necessities of life is concerned, then you cannot make successful in yogic life.
So there are so many rules and regulations. Those who are interested in yoga, you will find in the authorized books, yoga indriya-saṁyamaḥ: "The aim of yogic power, yogic success, is to control the senses." Our senses in this material world have been described as venomous serpents. Indriya-kāla-sarpa-paṭala. Kāla-sarpa, cobra, black cobra. So these indriyas are like that. Indriya means senses. As soon as touches, immediately it makes him poisonous. And that is the cause of our material conditional life. The more we are indulging unrestrictedly in sense gratification, we are becoming more and more entangled.
Therefore those who are very much addicted to the bodily necessities of life, for them this haṭha-yoga system . . . haṭha-yoga system means yama, niyama, aṣṭāṅga-yoga. It is called aṣṭāṅga-yoga. Yama, niyama, āsana, prāṇāyāma, dhyāna, dhāraṇā, pratyāhāra, samādhi. These things are in the aṣṭāṅga-yoga. The first thing is yama-niyama. One must have regulated life. That is called yama-niyama. Then practice āsana. There is mechanical process of sitting which will help you, concentration of the mind, āsana. Then praṇāyāma, concentration of the mind. Then meditation.