शमो दमस्तपः शौचं क्षान्तिरार्जवमेव च।
ज्ञानं विज्ञानमास्तिक्यं ब्रह्मकर्म स्वभावजम्।।18.42।।
18.42 The natural duties of the Brahmanas are the control of the internal and external organs, austerity, purity, forgiveness, straightforwardness, knowledge as also wisdom [Knowledge refers to the understanding of subjects presented by the scriptures; wisdom means making them matters of ones own experience.] and faith.
18.42 Sama is the control of the external sense-organs. Dama is the control of the mind. Tapas is the chastisement of the body by controlling enjoyments, as enjoined by the Sastras. Sauca is fitness for performing acts as enjoined by the Sastras. Ksanti is preserving the composure of the mind, though injured by others. Arjava is straightforwardness expressing itself in correct outward manifestation to others in consonance with ones own mind. Jnana is knowledge about the real nature of the higher and lower truths. Vijnana is the knowledge pertaining to exceptional attributes belonging to the Supreme Reality. Astikya or faith is firm conviction in the truth of all things enjoined in the Vedas. The meaning is that it is unshakable by any reason whatever. Astikya is positive conviction in the truth to the following effect: (1) The Lord Vasudeva, the Supreme Person, is signified by the term, Supreme Brahman. (2) He is devoid of even the slightest trace or evil. (3) He possesses countless hosts of auspicious and excellent attributes such as knowledge, strength etc., boundless and natural. (4) To reveal His nature is the sole purpose of the whole of Vedas and the Vedanta and He can be known only through them. (5) He is the sole cause of the universe (6) He is the foundation of the entire universe. (7) He is the actuator of all. (8) All actions taught in the Vedas form His worship. (9) When worshipped through them, He confers fruits known as Dharma, Artha, Kama and Moksa. That such is the meaning has been declared in the following text: Indeed I am to be known from all the Vedas (15.15); I am the origin of all; from Me proced everything (10.8), All this is strung on Me (7.7), Knowing me as the enjoyer of all sacrifices and austerities ৷৷. he attains peace (10.29), There is nothing greater than myself, Arjuna (7.7) He from whom proceeds the activity of all beings and by whom all this is pervaded - by worshipping Him with his duty, will a man reach perfection (18.46); and He who knows Me as unborn, without a beginning and the great Lord of the worlds ৷৷. (10.3) Such are the duties of the Brahmana arising from his inherent nature.
Shamo damastapah shaucham kshaantiraarjavameva cha; Jnaanam vijnaanam aastikyam brahmakarma swabhaavajam.
śhamaḥ—tranquility; damaḥ—restraint; tapaḥ—austerity; śhaucham—purity; kṣhāntiḥ—patience; ārjavam—integrity; eva—certainly; cha—and; jñānam—knowledge; vijñānam—wisdom; āstikyam—belief in a hereafter; brahma—of the priestly class; karma—work; svabhāva-jam—born of one’s intrinsic qualities