▁sought ▁to ▁investigate ▁the ▁sources ▁of ▁correct ▁knowledge ▁or ▁ep ist em ology . ▁ ▁Ny ā ya ▁tradition ally ▁accepts ▁four ▁Pr aman as ▁as ▁reliable ▁means ▁of ▁gain ing ▁knowledge ▁– ▁Pr aty ak ṣ a ▁( per ception ), ▁An um ā ṇ a ▁( in ference ), ▁Up am ā ṇ a ▁( com parison ▁and ▁anal ogy ) ▁and ▁Ś ab da ▁( word , ▁testim ony ▁of ▁past ▁or ▁present ▁reliable ▁exper ts ). ▁Ny ā ya ▁also ▁tradition ally ▁def ended ▁a ▁form ▁of ▁philosoph ical ▁real ism . ▁ ▁The ▁Ny ā ya ▁S ū tras ▁was ▁a ▁very ▁influ ential ▁text ▁in ▁Indian ▁philosophy , ▁lay ing ▁the ▁found ations ▁for ▁classical ▁Indian ▁ep ist em ological ▁deb ates ▁between ▁the ▁different ▁philosoph ical ▁schools . ▁It ▁includes , ▁for ▁example , ▁the ▁classic ▁H indu ▁rejo ind ers ▁against ▁Buddh ist ▁not - self ▁( an atta ) ▁arguments . ▁The ▁work ▁also ▁fam ously ▁arg ues ▁against ▁a ▁cre ator ▁God ▁( I sh var a ), ▁a ▁debate ▁which ▁became ▁central ▁to ▁H indu ism ▁in ▁the ▁medieval ▁period . ▁ ▁V ai ś e ṣ ika ▁V ai ś e ṣ ika ▁is ▁a ▁natural ist ▁school ▁of ▁atom ism , ▁which ▁accepts ▁only ▁two ▁sources ▁of ▁knowledge , ▁per ception ▁and ▁inference . ▁This ▁philosophy ▁held ▁that ▁the ▁universe ▁was ▁redu cible ▁to ▁param ā ṇ u ▁( at oms ), ▁which ▁are ▁ind est ruct ible ▁( an