The yoga process which is very much advertised in your country, that is more or less bodily exercise. Yoga process is very difficult for the modern age. I have several times discussed this point.
The preliminary process—yama, niyama, āsana, prāṇāyāma, dhyāna, dhāraṇā, samādhi—the eight processes, to control the senses, to control the mind, to practice sitting postures . . . under certain physical posture the mind become concentrated. So there are different āsanas.
Then meditation, then contemplation, then absorption. These things are preliminary process. But actually, the yoga means to attain ultimate benediction, niḥśreyasāya. What is that niḥśreyasāya? The spiritual realization. That is niḥśreyasāya.
Spiritual realization . . . there are different stages of spiritual realization. First spiritual realization is to understand oneself that "I am not matter; I am spirit." This is the first stage of spiritual realization—when one, firmly convinced . . . how? By knowledge. By knowledge. Just we are conscious, "I am Indian."
You are conscious that you are American. One is conscious, "I am Hindu." One is conscious, "I am Christian." So similarly, when one is fully conscious that, "I am spirit. Ahaṁ brahmāsmi, I am Brahman," that is the first spiritual realization, that knowledge. Knowledge means consciousness.
So this consciousness has also . . . a development of consciousness. There are different stages. And when one comes to the ultimate stage, niḥśreyasāya, that is called Kṛṣṇa consciousness, or God consciousness. And how that consciousness acts? That "I am a servant of God. I am servant of Kṛṣṇa." When this consciousness is firmly fixed up, this is called Kṛṣṇa consciousness.
Just like Caitanya Mahāprabhu: He presented Himself, nāhaṁ vipro na ca nara-patiḥ, no vanastho yatir vā (CC Madhya 13.80). He presented Himself . . . because He was Hindu and Vedic, followers of Vedic . . . but actually, He was not Hindu, because He's describing Himself nāham. Nāham means "I am not" "I am not." He's declining. What He's declining? "I am not Brāhmin, I am not Kṣatriya, I am not Vaiśya, I am not Śūdra, I am not brahmacārī, I am not gṛhastha, I am not vānaprastha, I am not sannyāsī."
The Vedic system of human life is divided into eight departmental activities, and that is going on under the name of Hinduism. It is now broken and degraded and so many things have happened. But actually, what is called Vedic system, that Vedic system is not meant for a particular class of men, but it is meant for the human society. Actually, human activities actually begins when they observe these eight principles of social divisions. More or less, they observe in any human society.
What is that? Brāhmin. Brāhmin means the most intelligent class of men of the society. Philosophers, scientists, astronomers, so many, intelligent class. So in every society there is a class of men who are very intelligent than ordinary men. Then Kṣatriya. Kṣatriya means . . . kṣat means harm. One who protects others from being harmed.
Suppose I am trying to harm you. And the person who protects you, he's Kṣatriya. And who protects you? The king or the government. Therefore, those who are engaged in governmental affairs or takes the administrative charge, they are called Kṣatriyas. So the Kṣatriyas, they are in every human society, the administrator class, politicians, diplomats.
Next Vaiśya, mercantile class. That is not to be explained. In your country there are so many mercantile class. And Śūdras. Śūdra means neither intelligent nor administrator nor merchant. General laborer. Give them something, they'll work. They have no intelligence. So they are called Śūdras. So these four divisions there are.
And . . . this is . . . so far our material necessities are concerned, there is need of intelligent class of men to guide, there is need of administrators or martial class of men, there is need of mercantile class of men, and there is need of laborer class of men. So these four divisions . . .
And next, culture. Culture means brahmacārī. First, student life. He's educated in the value of life. They are called brahmacārī. They're not allowed to mix with women. Just like nowadays, the schools and colleges, the boys and girls freely mix. The brahmacārī is not allowed to mix with girls and boys. That is restriction, brahmacārī.
Only gṛhasthas, householders, they are allowed to mix freely with woman, married. So brahmacārī is not allowed. That is spiritual training. In this way there are four department of spiritual training, namely brahmacārī; gṛhastha, or householder; vānaprastha, retired man and sannyas.