“The duties of Brāhmaṇas, Kṣatriyas, Vaiśyas and Śūdras are distributed according to the guṇas born of their own nature (guṇaiḥ svabhāva-prabhavaiḥ).” Once more (as at 4.13, 2.31) the Gītā grounds varṇa in svabhāva — innate temperament and aptitude — not in birth. The following verses (18.42–44) describe each by its qualities: the Brāhmaṇa by serenity, self-control, austerity, purity, knowledge; the Kṣatriya by valour, vigour, steadiness, generosity, leadership; the Vaiśya by the work of cultivation, cattle and trade; the Śūdra by service. Read honestly, this is a taxonomy of functions matched to natures, a division of labour keyed to psychology — not the hereditary, hierarchical caste-cage that later ages made of it.