Yoga Sutra 3.54 there is clear knowledge of two things

Sūtra III.53

From this (knowledge) there is clear knowledge of two things (seemingly) equivalent because they cannot be distinguished by class, characteristic, or position

What sort of things are knowable by that knowledge-born-of-discrimination? A particular field of the knowledge is now described: From this there is clear knowledge of two things (seemingly) equivalent because they cannot be distinguished by class, characteristic, or position.

A difference in class of the things may be the ground of differentiation of distinguishing the difference, as for instance, ‘This one is a cow, this one is a mare’.

When they both belong to one class, so that there is no difference in class, then When the class is the same, a characteristic (lakṣaṇa) an indicatory mark (liṅga) may be what differentiates them: ‘This cow has black eyes, that cow has lucky markings.’

When there is no difference of class, and no difference of characteristic, still a difference of position may be a ground for discerning the difference. If there are two myrobalan fruits, of the same class and with the same characteristics, then a difference in position may differentiate them: ‘This fruit is the front one, that is the one behind.’

But if the fruit in front is moved – while the observer is attending to something else so that his mind is distracted – to the position behind and the rear one to the front position, he will not be able to detect rightly which is which. That detection would have to come about by an infallible knowledge of truth about the particular situation in question, since that is what is present. And this is why it was said: From this -from the knowledge-born-of-discrimination – there is clear knowledge. From the knowledge-born-of-discrimination attained by saṃyama on instant and sequence, there is clear knowledge about them.

How is that? Its position at the instant of being the front fruit the position corresponding to being the front fruit is distinct from the position at the instant of being the fruit behind, the position corresponding to the fruit behind. The two fruits corresponding to the instant of being the front one and the one behind are distinct in their particular experiences of their own point-instants, having been affected by their positions at any given instant; at any instant their experiences are distinct, as they have been affected by the respective point-instants passed through. The difference of experience of the point-instants makes the difference between them.

This example illustrates how an expert yogin can, from the difference of their point-instants, get the idea of the difference between – can distinguish – even two ultimate atoms, by his direct perception (sākṣāt-karana) of the point-instant of the front atom, though it is identical in class and characteristic to the other atom, by his direct perception of the instant coincident with its position as the front atom; for when the one behind replaces it in that position by coming to the front position, the one that was behind is experiencing the front position at a different instant. In the case of the Lord and of the yogin, awareness of the distinction – discrimination of the difference (between the two atoms) – comes about from the difference between the instants.

On this point, however, there are others who maintain that it is the ultimate particulars the permanent ultimate atoms which alone make the idea of distinction, so that saṃyama on instants and their sequences is irrelevant. As the particulars constituting for example a jar, make the idea of its difference (from other jars, etc.), so it should be particulars consisting of ultimate atoms that give the idea of its existence, and the idea of them as its true existence; they also make the idea of difference in what they rest in (āśraya).

As to this it has been said: distinctions of location and characteristic, and distinctions of form, distance, and class are the causes of difference. This was in fact said in regard to physical things, but of course the ultimate atoms are changing every instant. If the ultimate particulars had been stable, difference would be determinable, but this could not apply to things incessantly changing.

When the atom in front changes into the atom behind, and the one behind into the front one, there are then no fixed ultimate particulars, so that knowledge of the distinction between them could not be attained from them. Necessarily then it could come only from that Knowledge-born-of-discrimination produced by saṃyama on the instant and its sequences. For it has been shown that ultimate atoms are not permanent entities, and therefore it is the distinction of the instants alone that is to be sought by the mind of the yogin.

He demonstrates the truth of the transience of ultimate atoms by citing the view of another ācārya. To this it is said: Since there is no difference of form or distance in the ultimate root-cause, there are no separate distinctions in the root – thus Vārṣaganya. To propose a plurality of pradhāna-s, one for each Field-knower (kṣetra-jña), on the ground that there should be many separate pradhāna-s because each should be the object of one single Puruṣa-purpose, would be contrary to reason, in view of the fact that they could have no difference of form or distance or class.

So at the basis of the ultimate atoms too, no separateness can be supposed. Therefore the conclusion is: a single root. For it is not right that the distinctions of ultimate atoms should be permanent, for they have forms and colours and so on, so that they can only be impermanent, like a jar.

Sūtra III.54

Knowledge-born-of-discrimination, having all, and all times, for its object, is called Transcendent

Knowledge-born-of-discrimination, having all, and all times, for its object, is called Transcendent (tāraka). This is a peak of knowledge, attained by gods, ṛṣi-s, gandharva-spirits and so on. It is called Transcendent, inasmuch as this Knowledge-born-of-discrimination, as it is said, flashes out spontaneously without any prompting from elsewhere. It cannot be taught by another, nor by teaching can it be grasped as it is. So that has all things as object, which means that there is nothing that does not become its object.

And with all times as its object: all things past, future and present, he knows them in all their variety with all their particulars at all times with all their changes. It grasps all at all times: without sequence, it arises in one instant, instantaneously, and not in a sequence, as with us.

This is the culmination of Knowledge-born-of discrimination; one ray of it is the yoga-light. This very ray of knowledge is the yoga and light, or again it is the light of yoga. What was begun undertaken in the Honeyed stage now has its culmination, the culmination of discriminative-Knowledge (viveka-jñāna). The various forms of knowledge associated with travelling at the speed of thought and so on, culminating in discriminative-Knowledge, are one ray of this.