A brāhmaṇa, it is the duty of the brāhmaṇa to see that his son is being properly trained up as a brāhmaṇa. Satyaṁ śamo damas titikṣā ārjavaṁ brahma-karma svabhāva-jam (BG 18.42). Everything is there. The brāhmaṇas should be taught how to become truthful, first of all. A brāhmaṇa will never speak lie, at any cost. It is stated that even if his enemy inquires something confidential from him, he'll say, "Yes, this is my position." This is truthfulness. He'll not even, I mean to say, guile, against his enemy. He should be truthful. Even kṣatriyas, they are also truthful men. Truthfulness is so valuable. That makes one powerful brāhmaṇa. Satyam.
There is an instance how a brāhmaṇa is recognized. Satyakam yavala(?). Upaniṣads. This satyakam went to Gautama Muni. "Sir, please make me your disciple." So according to Vedic principle, without becoming a brāhmaṇa he cannot be accepted as disciple. Without becoming brāhmaṇa.