 Before we start out with the definitions, the following observation may be noted. It is true that the classical Indian philosophers were seriously concerned with the notions of enlightenment, the highest good, freedom from the cycle of rebirth and the attainment of ultimate bliss, etc. Therefore, some even question whether they were concerned with any epistemological questions at all, much less the ones raised here? But they were! For Naiyāyikas, in particular, this was a major focus: the reason offered in the early Nyāya tradition, in Vātsyāyana’s (c. 450–500 CE) commentary on the Nyāya-sūtra, is that without knowledge of objects there is no success in practical response to them. Not very enlightening, perhaps. However, a much sharper justification comes from Gaṅgeśa (c. 12th century CE), the founder of the Navya-Nyāya school, in the introduction to his great work, Jewel Of Reflection On The Truth (Tattvacintāmaṇi):