Before delivering the technical breakdown, Krishna cites His sources, validating the knowledge. He says: This profound knowledge regarding the field and the knower has already been sung and described in many diverse ways (bahudhā gītaṃ) by the great, enlightened sages of the past (ṛṣibhir). It has been analyzed distinctly and separately (pṛthak) within the various poetic meters of the Vedic hymns (chandobhir vividhaiḥ). And furthermore, it is specifically, rigorously, and logically presented (caiva) in the exact aphorisms of the Brahma-sūtra (brahma-sūtra-padaiś), perfectly supported by conclusive reasoning, logic, and cause-and-effect (hetumadbhir viniścitaiḥ).