The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
17. If it be said that this is not so, on account of the inferential marks of the individual soul and the chief vital air; we reply that that has already been explained.
It remains for us to refute the objection that on account of the inferential marks of the individual soul and the chief vital air, which are met with in the complementary passage, either the one or the other must be meant in the passage under discussion, and not the highest Lord.--We therefore remark that that objection has already been disposed of under I, 1, 31. There it was shown that from an interpretation similar to the one here proposed by the pûrvapakshin there would result a threefold meditation one having Brahman for its object, a second one directed on the individual soul, and a third one connected with the chief vital air. Now the same result would present itself in our case, and that would be unacceptable as we must infer from the introductory as well as the concluding clauses, that the passage under discussion refers to Brahman. With reference to the introductory clause this has been already proved; that the concluding passage also refers to Brahman, we infer from the fact of there being stated in it a pre-eminently high reward, 'Warding off all evil he who knows this obtains pre-eminence among all beings, sovereignty, supremacy.'--But if this is so, the sense of the passage under discussion is already settled by the discussion of the passage about Pratardana (I, 1, 31); why, then, the present Sûtra?--No, we reply; the sense of our passage is not yet settled, since under I, 1, 31 it has not been proved that the clause, 'Or he whose work is this,' refers to Brahman. Hence there arises again, in connexion with the present passage, a doubt whether the individual soul and the chief vital air may not be meant, and that doubt has again to be refuted.--The word prâna occurs, moreover, in the sense of Brahman, so in the passage, 'The mind settles down on prâna' (Kh. Up. VI, 8, 2).--The inferential marks of the individual soul also have, on account of the introductory and concluding clauses referring to Brahman, to be explained so as not to give rise to any discrepancy.