Nyāya Sūtras 81

And in this way all means of valid cognition would be eliminated; therefore he says:

Not so, because their establishment is like the establishment of the light of a lamp.

Just as the light of a lamp, because it is an auxiliary factor in perception, is a means of valid cognition in the seeing of visible things, and it is grasped through another perception by contact with the eye; it is inferred as the cause of seeing because seeing occurs or does not occur according to the presence or absence of the lamp; [and] it is also understood through the authoritative instruction: ‘Take a lamp in the dark’;—likewise, apprehension of perception and the others is indeed through perception and the others according to observation. The sense organs, to begin with, are inferred precisely through the grasping of their respective objects. Objects are grasped perceptually. The contacts of sense organ and object, however, are inferred through the mark of obstruction.

Knowledge arisen from the contact of sense organ and object is grasped—like pleasure and the like—from the particular conjunction of self and mind, and because of its inherence in the self. In this way, the particulars of the means of valid cognition should be stated distinctly. And just as the light of a lamp, being an object of vision, is the cause of the seeing of other objects of vision and thus obtains the status of [both] object of vision and seeing, so too a particular class of objects, being an object of valid cognition, obtains the status of [both] means of valid cognition and object of valid cognition because it is a cause of apprehension. Thus this apprehension of perception and the others is precisely through perception and the others according to observation; it is not through another means of valid cognition, nor is it without a means of proof in the absence of a means of valid cognition. If it is objected that an entity cannot be grasped by that very entity itself; no, because of the community of definition despite difference of object. [The opponent says:] ‘The grasping of perception and the others precisely by perception and the others is improper, for one thing is observed to be grasped by another.’ [We reply:] No, because of the community of definition despite difference of object: through the definition of perception multiple objects are comprehended, and among them one is grasped by another, so there is no fault. The same applies to inference and the others as well; just as water drawn up [by a vessel] grasps [i.e., detects] water situated in a reservoir.

And because of the observation of the knower and the mind: in the form ‘I am happy’, ‘I am miserable’, the grasping of that very knower by that very knower is observed. And in ‘The non-arising of simultaneous cognitions is the mark of the mind’, the inference of that very mind by that very mind is observed, so there is non-difference between the knower and the knowable, and non-difference between the grasping and the graspable. If it is objected that there is a difference of instrumental cause here, it is the same [in our case]: a knower does not know himself without another instrumental cause, nor is the mind grasped by the mind without another instrumental cause—this is the same; here too, in the grasping of perception and the others by perception and the others, difference of object is not lost. And because of the impossibility of a non-domain for perception and the others: if there were some class of objects that was not a domain of perception and the others, which could not be grasped by perception and the others, another means of valid cognition would have to be adopted for grasping it; but that cannot be demonstrated by anyone. Everything, both existent and non-existent, is the domain of perception and the others, exactly according to observation.