Nyāya Sūtras 202

And as for what was said: "Because of the restriction of objects"—

There is no negation, precisely because of that restriction, since the self exists.

If indeed a single sense organ had indefinite objects, were omniscient, grasped all objects, and were conscious, who could infer a conscious [self] distinct from it? But because the sense organs have restricted objects, therefore a conscious [agent] distinct from them, omniscient, grasping all objects, and transcending what is restricted by objects, is inferred. Regarding this, here is cited an irrefutable indication consisting in the operation of a conscious [agent]: Having seen a color, this [agent] indeed infers a previously grasped taste or smell; and perceiving a smell, he infers color and taste. The same should be stated regarding the remaining objects as well. Having seen a color, he smells an odor; and having smelled an odor, he sees a color. Thus, he synthesizes this apprehension of all objects, which has no fixed sequence, possesses a single conscious substratum, and has no other agent;

having synthesized, as having himself as agent, the cognitions of perception, inference, testimony, and doubt having various objects, he experiences [them]; he comprehends treatises dealing with all objects; hearing sequentially occurring letters which are objects not [per se] an object of the ear, having synthesized them as words and sentences, and understanding the conventional relation between words and meanings, he grasps a manifold collection of objects that cannot be grasped by each sense organ alone. This infinite variety of knowable objects of an omniscient [self] cannot possibly be gone through step by step; only a mere outline has been cited. Therefore, what was asserted—"if the sense organs are conscious, what is the use of this conscious [self]?"—that is improper. (3)