These four divisions are very scientific. Another four divisions—brahmacārī, gṛhastha—four divisions of the order of working: brahmin, kṣatriya, vaiśya, śūdra. This combined eight system in the human society is called perfect human society. Where these four . . . eight divisions of spiritual and material advancement of life is not there existing, that means that is not human society. They are required.
So here it is explained that either you be brahmacārī or gṛhastha or vānaprastha or sannyāsa, everyone's business is Kṛṣṇa, cultivate Kṛṣṇa consciousness. Or either you become a brahmin or a kṣatriya or a vaiśya or the . . . brahmin intelligent class of men; kṣatriya means politicians, administrative class of men; vaiśya means mercantile class of men; and śūdra means general worker. So either you are brahmin or a kṣatriya—whatever you may be—it doesn't matter.
Just like my different parts, limbs, of the body are situated in different parts to function differently. Hand's function is different from the leg's function. The mouth's function is different from the genitals' function. Although they are situated for executing different function, the whole aim is targeted to maintenance of this body. Similarly, whatever you may be, you do not require to change your position. You remain a brahmacārī, gṛhastha, worker, laborer, brahmin —whatever you may be, that doesn't matter—you just engage yourself in Kṛṣṇa consciousness. That is your duty.
The hand's function is different from the leg's function, but both the hands and the legs are engaged for serving the whole body. Similarly, you may become an engineer or a medical practitioner, a businessman or worker, this or that—that doesn't matter. Please engage yourself in Kṛṣṇa consciousness, and your life will be success. This is the Kṛṣṇa consciousness movement.