Yoga Sutra 1.04 there is only one sight, and the sight is knowledge alone.

Sūtra I.4

Otherwise, it conforms itself to the mental process

(Opponent) If though it is so means that power-of-consciousness does rest in its own nature even when mind is extraverted, and not so denies that it so rests, there is the contradiction that the same thing both is so and is not so, and our side asks in bewilderment, How can this be?

(Answer) The answer from our side is, Otherwise, it conforms itself to the mental process.

(Opponent) Well, why does it conform to it?

(Answer) Because objects have been displayed to it. Though in the two cases there is no distinction as to the resting in its own nature, still there is a distinction according to whether it conforms to the mental processes or not, and so it is not a contradiction between being so and being not so.

(Opponent) Connection with conformity to a mental process is connection with a different state, and must entail defects like changeability.

(Answer) The answer lies in the fact that objects have been displayed to it. The apparent change is not intrinsic but projected (adhyāropita), like a crystal’s taking on the colour of something put near it.

In the extraverted state outside the inhibited state whatever the process in the mind tainted or untainted, there is a process not distinguished from it, like it, which is natural to this one (Puruṣa). Without a process in the mind, and without this nature (of Puruṣa), there would be no process in Puruṣa. There is always something known to Puruṣa, so no change is involved in him.

There is a sūtra by an earlier teacher (ācārya): There is only one sight, and the sight is knowledge (khyāti) alone. There is only one sight (darśana) of buddhi and of Puruṣa. What does this mean? The sight is knowledge alone. Sight is a process of the mind (buddhi). It is a knowledge in the sense that it is known by Puruṣa; it is also knowledge in the sense that by it the nature of buddhi and of Puruṣa is known. It is an instrument in that the form of the object is apprehended by it, and it is an object inasmuch as it is apprehended by its own nature as knowledge; similarly, it is a sight in that it is seen, and also sight in that things are seen by it; it is knowledge (jñāna) in that it is known and also that things are known by it. This is how it is all to be understood.

(Opponent) But mind itself is the knowing agent (khyātikartṛ); it is that which is known and which knows. There is no need to suppose any other knowing.

(Answer) That we shall refute when we come to the sūtra, (Mind) is not self-illumining because it is something perceived (IV.19).

(Opponent) If all this is simply manifested (parivjṛmbhita) by mind, and Puruṣa sits apart, how can he be the experiencer (bhoktṛ)?

(Answer) Why not? Agents (kāraka) are of various kinds. Some are operational, and some are effective by mere proximity without any operation. When we say that one cooks, the man active in putting things on the fire and so on is called the agent; the pot, though not performing any operation by its holding and supporting the food, is still called a ‘cooker’. The space in the pot itself does provide a place for the food, but we do not take this to be an operation by it.

Again, there is the king who is an agent by merely appearing (at the council), whereupon all the (ministerial) agencies become agents carrying out their own operations. The sun does not look to some external instrument for his shining, nor does he perform any operation. He does not produce some previously non-existent shining as he comes and goes. It is simply that shining is his nature. So he is said to illumine by proximity alone, manifesting jars and so on as bright forms.

In our present case too, the mental processes, pervaded by his nature as consciousness (cid-ātman), are seen by Puruṣa who is pure sight.

To show how Puruṣa is the seer he now says:

Even the philosopher who holds that knowledge (jñāna) arises from a conjunction of the self (ātman) and mind (manas), calls the self the knower (jñātṛ), as pervading the known object by knowledge, not as performing an operation. Knowledge too, being (in his view) an attribute (guṇa) of the self, is without action; it is simply its nature to show objects. It cannot be maintained that a man cannot be said to know without some action, for a man is said to know when he pervades the object with knowledge.

If, however, new knowledge is assumed from conjunction of the self and mind, that knowledge belongs to self and not to the mind, for it is said that he knows, and not that his mind knows. Why?

(Opponent) Admitted, but the reason is that the self is what we call the inherent cause (samavāyī-kāraṇa, having knowledge as an attribute).

(Answer) That has not been established. Just as what had to be demonstrated was, why the knowledge should belong to the self (and not to the mind), so it would have to be demonstrated why self should be the inherent cause, and not mind, inasmuch as you maintain that mind is not itself the self, and that knowledge arises from conjunction of the two.

(Opponent) Let it be because of the recollection in memory of the saṃskāra, laid down by the knowledge, of the self as the sole agent.

(Answer) No, for that too would have to be demonstrated. In that case also it has to be shown why the saṃskāra of knowledge and the recollection of the memory should relate only to the self and not to the mind.

(Opponent) Let us say that it is because desire (icchā, an attribute of self in our system) and its fulfilment are (referred to) the same place.

(Answer) No, again it is the same thing. Once (it is accepted that) they are produced by a conjunction, it cannot be shown why the results and the desire should pertain to self alone and not to mind.

Moreover, this knowledge too is accepted (by you) to be a knowable object, so an infinite regress will follow. And it cannot be that one knowledge should be known by the instrument of another knowledge, and that by another, and that by another, endlessly.

To avoid the regress, one might say that at some point there is a knowledge which is primary, perceived not by some other knowledge but spontaneously by itself alone. But this would imply that (other) objects too should be able to perceive themselves spontaneously, just as knowledge is held to do.

(Opponent) Let us say that knowledge itself shines, and it makes others shine, being naturally luminous like a lamp, and so there is no defect in the argument, because nothing else is naturally luminous.

(Answer) Then even things like lights would never be known.

(Opponent) Well, knowledge knows spontaneously because it is an attribute of the self, and is luminous by nature as well, whereas things like lights which shine outwards are of opposite character to knowledge. So the argument holds.

(Answer) Not that either. If to be an attribute of the self and also luminous by nature were a cause for spontaneous knowing by knowledge, everyone would be omniscient.

(Opponent) There also has to be some knowable form.

(Answer) Not even that. (For knowledge to know itself) the cause of one knowledge would be the fact of the form of another knowledge, and in the same way, the form of the first knowledge as a knowable would cause yet another knowledge, and so the regress would be unavoidable.

Furthermore, no example is found to instance anything being subject and object for itself; even a light needs an eye to be known. Nor (can it be said that there) are two parts in knowledge, since it has no parts.

Even if it had, since they would both be luminous, they could not be subject and object to each other, any more than two lights.

Furthermore, if being both subject and object were accepted of knowledge, it could never be the real nature of the self.

Therefore knowledge of objective forms, and memory, and its recall, and effort and desire and so on, are all essentially not-self, because they are objects of knowledge like outer forms, and because they exist-for-another (parārtha) as is shown by their dependence on the body-mind aggregate for the manifestation of their forms and other qualities. So because they have dependence, and are impermanent, and are accompanied by effort – for these and similar reasons it is certain that they are essentially not-self.

Mind is as it were a magnet. As a magnet serves to pervade with itself the iron, by merely being placed near it, so the mind serves to pervade with itself the self (ātman) which is pure consciousness, by the fact of being seen by it. It is spoken of as like a dancing-girl, because it puts on a display, by means of the inner-organ (antaḥkaraṇa – thought, emotion and so on). Here mind (citta) is the one who puts on the display, and Puruṣa is the one who sees it.

(Opponent) How does this distinction come about?

(Answer) It comes about as the relation of a thing to its owner.

(Opponent) But how does the relation of thing and owner come about?

(Answer) It is the nature of each.

(Opponent) What is this nature?

(Answer) Mind is comparable to a magnet.

(Opponent) What is the cause of Puruṣa’s being aware of the mind process?

(Answer) A magnet serves by mere proximity, the mind by the fact of being seen. There is a beginningless relation, and this is the cause of Puruṣa’s awareness of the mental processes.