The Yaksha asked,—‘By what, O king, birth, behaviour, study, or learning doth a person become a Brahmana? Tell us with certitude!’ Yudhishthira answered,—‘Listen, O Yaksha! It is neither birth, nor study, nor learning, that is the cause of Brahmanahood, without doubt, it is behaviour that constitutes it. One’s behaviour should always be well-guarded, especially by a Brahmana. He who maintaineth his conduct unimpaired, is never impaired himself. Professors and pupils, in fact, all who study the scriptures, if addicted to wicked habits, are to be regarded as illiterate wretches. He only is learned who performeth his religious duties. He even that hath studied the four Vedas is to be regarded as a wicked wretch scarcely distinguishable from a Sudra (if his conduct be not correct). He only who performeth the Agnihotra and hath his senses under control, is called a Brahmana!’

In plain words: Asked what makes someone a true Brahmana (a priest or spiritual person), Yudhishthira says it is not birth, study or learning but good behavior. Even someone who has studied all four Vedas, the holy scriptures, is no better than a wretch if he acts badly; only one who does his religious duties, like the Agnihotra fire ritual, and controls his senses is truly a Brahmana.