The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
6. If it is said that (the word 'seeing') has a figurative meaning, we deny that, on account of the word Self (being applied to the cause of the world).
Your assertion that the term 'Being' denotes the non-intelligent pradhâna, and that thought is ascribed to it in a figurative sense only, as it is to fire and water, is untenable. Why so? On account of the term 'Self.' For the passage Kh. Up. VI, 2, which begins 'Being only, my dear, this was in the beginning,' after having related the creation of fire, water, and earth ('it thought,' &c.; 'it sent forth fire,' &c.), goes on--denoting the thinking principle of which the whole chapter treats, and likewise fire, water, and earth, by the term--'divinities'--as follows, 'That divinity thought: Let me now enter those three divinities with this living Self (gîva. âtman) and evolve names and forms.' If we assumed that in this passage the non-intelligent pradhâna is figuratively spoken of as thinking, we should also have to assume that the same pradhâna--as once constituting the subject-matter of the chapter--is referred to by the term 'that divinity.' But in that case the divinity would not speak of the gîva as 'Self.' For by the term 'Giva' we must understand, according to the received meaning and the etymology of the word, the intelligent (principle) which rules over the body and sustains the vital airs. How could such a principle be the Self of the non-intelligent pradhâna? By 'Self' we understand (a being's) own nature, and it is clear that the intelligent Giva cannot constitute the nature of the non-intelligent pradhâna. If, on the other hand, we refer the whole chapter to the intelligent Brahman, to
which thought in its primary sense belongs, the use of the word 'Self' with reference to the Gîva is quite adequate. Then again there is the other passage, 'That which is that subtle essence, in it all that exists has its self. It is the true. It is the Self. That art thou, O Svetaketu' (Kh. Up. VI, 8, 7, &c.). Here the clause 'It is the Self' designates the Being of which the entire chapter treats, viz. the subtle Self, by the word 'Self,' and the concluding clause, 'that art thou, O Svetaketu,' declares the intelligent Svetaketu to be of the nature of the Self. Fire and water, on the other hand, are non-intelligent, since they are objects (of the mind), and since they are declared to be implicated in the evolution of names and forms. And as at the same time there is no reason for ascribing to them thought in its primary sense--while the employment of the word 'Self' furnishes such a reason with reference to the Sat--the thought attributed to them must be explained in a figurative sense, like the inclination of the river-bank. Moreover, the thinking on the part of fire and water is to be understood as dependent on their being ruled over by the Sat. On the other hand, the thought of the Sat is, on account of the word 'Self,' not to be understood in a figurative sense. 1
Here the Sânkhya comes forward with a new objection. The word 'Self,' he says, may be applied to the pradhâna, although unintelligent, because it is sometimes figuratively used in the sense of 'that which effects all purposes of another;' as, for instance, a king applies the word 'Self' to some servant who carries out all the king's intentions, 'Bhadrasena is my (other) Self.' For the pradhâna, which effects the enjoyment and the emancipation of the soul, serves the latter in the same way as a minister serves his king in the affairs of peace and war. Or else, it may be said, the one word 'Self' may refer to non-intelligent things as well as to intelligent beings, as we see that such expressions as 'the Self of the elements,' 'the Self of the senses,' are made use of, and as the one word 'light' (gyotis) denotes a certain
sacrifice (the gyotishtoma) as well as a flame. How then does it follow from the word 'Self' that the thinking (ascribed to the cause of the world) is not to be taken in a figurative sense?
To this last argumentation the Sûtrakâra replies:
54:1 So that, on this latter explanation, it is unnecessary to assume a figurative sense of the word 'thinking' in any of the three passages.