The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
20. The one within (the sun and the eye) (is the highest Lord), on account of his qualities being declared 3.
The following passage is found in Scripture (Kh. Up. I, 6, 6 ff.), "Now that person bright as gold who is seen within
the sun, with beard bright as gold and hair bright as gold, bright as gold altogether to the very tips of his nails, whose eyes are like blue lotus; his name is Ut, for he has risen (udita) above all evil. He also who knows this rises above all evil. So much with reference to the devas.' And further on, with reference to the body, 'Now the person who is seen in the eye,' &c. Here the following doubt presents itself. Do these passages point out, as the object of devotion directed on the sphere of the sun and the eye, merely some special individual soul, which, by means of a large measure of knowledge and pious works, has raised itself to a position of eminence; or do they refer to the eternally perfect highest Lord?
The pûrvapakshin takes the former view. An individual soul, he says, is referred to, since Scripture speaks of a definite shape. To the person in the sun special features are ascribed, such as the possession of a beard as bright as gold and so on, and the same features manifestly belong to the person in the eye also, since they are expressly transferred to it in the passage, 'The shape of this person is the same as the shape of that person.' That, on the other hand, no shape can be ascribed to the highest Lord, follows from the passage (Kau. Up. I,3,15), 'That which is without sound, without touch, without form, without decay.' That an individual soul is meant follows moreover from the fact that a definite abode is mentioned, 'He who is in the sun; he who is in the eye.' About the highest Lord, who has no special abode, but abides in his own glory, no similar statement can be made; compare, for instance, the two following passages, 'Where does he rest? In his own glory?' (Kh. Up. VII, 24, 1); and 'like the ether he is omnipresent, eternal.' A further argument for our view is supplied by the fact that the might (of the being in question) is said to be limited; for the passage, 'He is lord of the worlds beyond that, and of the wishes of the devas,' indicates the
limitation of the might of the person in the sun; and the passage, 'He is lord of the worlds beneath that and of the wishes of men,' indicates the limitation of the might of the person in the eye. No limit, on the other hand, can be admitted of the might of the highest Lord, as appears from the passage (Bri. Up. IV, 4, 22), 'He is the Lord of all, the king of all things, the protector of all things. He is a bank and a boundary so that these worlds may not be confounded;' which passage intimates that the Lord is free from all limiting distinctions. For all these reasons the person in the eye and the sun cannot be the highest Lord.
To this reasoning the Sûtra replies, 'The one within, on account of his qualities being declared.' The person referred to in the passages concerning the person within the sun and the person within the eye is not a transmigrating being, but the highest Lord. Why? Because his qualities are declared. For the qualities of the highest Lord are indicated in the text as follows. At first the name of the person within the sun is mentioned--'his name is Ut'--and then this name is explained on the ground of that person being free from all evil, 'He has risen above all evil.' The same name thus explained is then transferred to the person in the eye, in the clause, 'the name of the one is the name of the other.' Now, entire freedom from sin is attributed in Scripture to the highest Self only; so, for instance (Kh. Up. VIII, 7, 1), 'The Self which is free from sin,' &c. Then, again, there is the passage, 'He is Rik, he is Sâman, Uktha, Yagus, Brahman,' which declares the person in the eye to be the Self of the Rik, Sâman, and so on; which is possible only if that person is the Lord who, as being the cause of all, is to be considered as the Self of all. Moreover, the text, after having stated in succession Rik and Sâman to have earth and fire for their Self with reference to the Devas, and, again, speech and breath with reference to the body, continues, 'Rik and Sâman are his joints,' with reference to the Devas, and 'the joints of the one are the joints of the other,' with reference to the body. Now this statement
also can be made only with regard to that which is the Self of all. Further, the passage, 'Therefore all who sing to the Vînâ sing him, and from him also they obtain wealth,' shows that the being spoken of is the sole topic of all worldly songs; which again holds true of the highest Lord only. That absolute command over the objects of worldly desires (as displayed, for instance, in the bestowal of wealth) entitles us to infer that the Lord is meant, appears also from the following passage of the Bhagavadgîtâ (X, 41), 'Whatever being there is possessing power, glory, or strength, know it to be produced from a portion of my energy 1.' To the objection that the statements about bodily shape contained in the clauses, 'With a beard bright as gold,' &c., cannot refer to the highest Lord, we reply that the highest Lord also may, when he pleases, assume a bodily shape formed of Mâyâ, in order to gratify thereby his devout worshippers. Thus Smriti also says, 'That thou seest me, O Nârada, is the Mâyâ emitted by me; do not then look on me as endowed with the qualities of all beings.' We have further to note that expressions such as, 'That which is without sound, without touch, without form, without decay,' are made use of where instruction is given about the nature of the highest Lord in so far as he is devoid of all qualities; while passages such as the following one, 'He to whom belong all works, all desires, all sweet odours and tastes' (Kh. Up. III, 14, 2), which represent the highest Lord as the object of devotion, speak of him, who is the cause of everything, as possessing some of the qualities of his effects. Analogously he may be spoken of, in the passage under discussion, as having a beard bright as gold and so on. With reference to the objection that the highest Lord cannot be meant because an abode is spoken of, we remark that, for the purposes of devout meditation, a special abode may be assigned to Brahman, although it abides in its own glory only; for as Brahman is, like ether, all-pervading, it may be viewed as
being within the Self of all beings. The statement, finally, about the limitation of Brahman's might, which depends on the distinction of what belongs to the gods and what to the body, has likewise reference to devout meditation only. From all this it follows that the being which Scripture states to be within the eye and the sun is the highest Lord.
77:3 The preceding adhikarana had shown that the five Selfs (consisting of food, mind, and so on), which the Taitt. Up. enumerates, are introduced merely for the purpose of facilitating the cognition of Brahman considered as devoid of all qualities; while that Brahman p. 78 itself is the real object of knowledge. The present adhikarana undertakes to show that the passage about the golden person represents the savisesha Brahman as the object of devout meditation.
80:1 So that the real giver of the gifts bestowed by princes on poets and singers is Brahman.