Everything should be learned from the standard Vedic literature, and society and other things, economic development, everything. So that is here in the Bhagavad-gītā. All problems, whatever you want, you consult Bhagavad-gītā—you'll have perfect answer. That is called Vedic literature. Perfect, without any flaw, you'll get. But to understand Vedic literature one has to become a brāhmaṇa or a kṣatriya. Even in vaiśya stage or śūdra stage no possible, not possible. Vaiśya stage, little, but in brāhmaṇa stage and kṣatriya stage people are intelligent. Therefore Bhagavad-gītā is said, Kṛṣṇa begins in the Fourth Chapter, imaṁ rājarṣayo viduḥ (BG 4.2). Rājarṣayaḥ means king, kṣatriya, with qualification of brāhmaṇa. He has got . . . although he is king, he is not brāhmaṇa, but he has got the qualification of brāhmaṇa.
So that qualification of brāhmaṇa can be fully attained if one becomes Vaiṣṇava. Vaiṣṇava is transcendental even to the brāhmaṇa. Sa guṇān samatītyaitān brahma-bhūyāya kalpate (BG 14.26). He becomes transcendental to the stage of all the three modes of material nature. There are three modes of material nature: sattva-guṇa, rajo-guṇa, tamo-guṇa. Sattva-guṇa is the stage of brāhmaṇa, rajo-guṇa is the stage of kṣatriya, and tamo-guṇa is the stage of śūdra, and mixed together is the stage of vaiśya. Vaiśya has mixed quality; and pure sattva-guṇa, brāhmaṇa; pure rajo-guṇa, kṣatriya.