Nyāya Sūtras 2.13

2.13

so 'yam anavayavena tantrārtha uddiṣṭo veditavyaḥ/ ātmādeḥ khalu prameyasya tattvajñānān niḥśreyasādhigamaḥ/

This is to be known as the subject matter of the treatise stated in its entirety. Attainment of the highest good results indeed from the knowledge of reality of the object of valid cognition, beginning with the self.