caturbhiś ca prakāraiḥ vidyopayuktā
caturbhiś ca prakāraiḥ vidyopayuktā bhavati, āgama-kālena svādhyāya-kālena pravacana-kālena vyavahāra-kāleneti |
(Mahābhāṣya: 1.1.1)
“Knowledge is acquired in four ways: at the time of receiving [it from an ācārya], at the time of personally studying [it, i.e., reviewing it, reflecting on it, reciting it, etc.], at the time of speaking [i.e., teaching it to others], and at the time of applying [it, i.e., performing sacrifices, navigating challenges, etc.].”