tadgrāhyavastvapekṣaṃ hi prāmāṇyaṃ tasya gīyate / parato 'vagates tasya prameyatvavyavasthitiḥ //
The validity of [that] cognition is always asserted in reference to the object apprehended by it; and since its validity is apprehended from another [cognition], that [first cognition] becomes established as something to be cognized.