Nyāya Sūtras 2.4

2.4

so 'yaṃ pramāṇārtho 'parisaṅkhyeyaḥ, prāṇabhṛdbhedasyāparisaṅkhyeyatvāt/ arthavati ca pramāṇe pramātā prameyaṃ pramitir ity arthavanti bhavanti/ kasmāt? anyatamāpāye 'rthasyānupapatteḥ/

This object of the means of valid cognition is innumerable, because the varieties of living beings are innumerable. And when the means of valid cognition has purpose, the cognizer, the object of valid cognition, and the valid cognition also have purpose. Why? Because if any one of them were absent, the object could not be established.