By observing the duties sanctioned for him, and by studying the Vedas and other scriptures, one becomes a twice-born one whether one does any other deed or not, he becomes a Brahmana by becoming the friend of all creatures.
परिनिष्ठितकार्यो हि स्वाध्यायेन द्विजो भवेत्। कुर्यादन्यन्न वा कुर्यान्मैत्रो ब्राह्मण उच्यते॥