There are three guṇas. The material world is conducted by three guṇas, means the quality of goodness, the quality of passion, the quality of ignorance, and mixed. So first, second, third, and the mixed is called fourth. That is called varṇāśrama. Cātur-varṇyam. Guṇa-karma-vibhāgaśaḥ (BG 4.13): according to quality and karma. So the first-, second-, and third-class division, they are all dvijas, twice-born. Brāhmaṇa, kṣatriya and vaiśya. Dvija means saṁskāra, reformation, to mold the character. That is called saṁskāra.
Just like you can train even a tiger, even an animal, to dance according to your desire. That is practical. So you cannot train a human being to become a brāhmaṇa? With such intelligence? But there is no such training. They are simply training all cats and dogs. But the Vedic civilization takes this opportunity of human being, to make him perfect in his life. What is that perfection? That perfection is to understand God and become His devotee. That is perfection. Not that to become very stout and strong, as strong as the tiger or as cunning as the jackal. Not that. That is not training.
So according to division, the training was there. The first-class training is brāhmaṇa. Brāhmaṇa means they must be truthful first. Satya śamo damas titikṣā (BG 18.42). They must be able to control the senses, control the mind. Satya śamo damas titikṣā. Must be tolerant, titikṣā; ārjava, very simple; jñānam, full knowledge; vijñānam, practical application in life. Satya śamo damas titikṣā. Śuciḥ, cleanliness. Brahma-karma svabhāva-jam. So they should be trained. A class of men should be trained for these qualities. They are called brāhmaṇa. Similarly, another class, second class, they should be trained up as kṣatriya, very powerful, never goes away from the challenge of fighting. Yuddhe cāpy apalāyanam.