The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut [1896] at sacred-texts.com
10. Those (qualities which are attributed to the subject of a vidyâ in one Sâkhâ only) (are to be inserted) in other places (also), since (the vidyâs) are non-different on the whole.
In the colloquy of the prânas recorded by the Vâgasaneyins and the Khandogas the prâna, endowed with various qualities such as being the best and so on, is represented as the object of meditation, and various qualities such as being the richest and the like are ascribed to speech and the other organs. And these latter qualities are in the end attributed to the prâna also, 'If I am the richest thou art the richest,' &c. Now in other Sâkhâs also, as e.g. that of the Kaushîtakins, the former set of qualities such as being the best and so on is ascribed to the prâna (cp. Kau. Up. II, 14, 'Now follows the Nihsreyasâdâna,' &c.), but at the same time the latter set of attributes, viz. being the richest and so on, is not mentioned.--The question then is whether those qualities which are mentioned in some places only are, for the purposes of meditation, to be inserted there also where nothing is said about them.
They are not so to be inserted, the pûrvapakshin maintains, on account of the employment of the word 'thus.' In the Kaushîtakin-text we meet with the clause, 'He who knows thus, having recognised the pre-eminence in prâna.' Now the word 'thus' which here indicates the object of knowledge always refers to something mentioned not far off, and cannot therefore denote a set of qualities mentioned in other Sâkhâs only. We therefore maintain that each of the colloquies of the prânas must be considered complete with the qualities stated in itself.
To this we make the following reply. The qualities mentioned in one text are to be inserted in the other corresponding texts also, 'Since on the whole they are non-different,' i.e. because the prâna-vidyâs are recognised to be the same in all essential points. And if they are the same,
why should the qualities stated in one not be inserted in the others also?--But how about the objection founded by the pûrvapakshin on the employment of the word 'thus?'--Although it is true, we reply, that the word 'thus' in the Kaushtîakin-brâhmana does not denote the set of qualities mentioned in the Vâgasaneyin-brâhmana, yet that set of qualities is denoted by the 'thus' met within the Vâgasaneyin-brâhmana, while the vidyâ is, as proved by us, one and the same; hence no difference has to be made between qualities mentioned in one's own Sâkhâ and qualities mentioned in another Sâkhâ, as long as the vidyâ is one and the same. Nor does this by any means imply a disregard of the text of scripture, and the assumption of things not warranted by the text. The qualities declared in one Sâkhâ are valid for all scripture as long as the thing to which the qualities belong is the same. Devadatta, who in his own country is known to possess valour and certain other qualities, does not lose those qualities by going to a foreign land, although the inhabitants of that land may know nothing about them. And through better acquaintance his qualities will become manifest to the people of the foreign country also. Similarly the qualities stated in one Sâkhâ may, through special application, be inserted in another Sâkhâ.--Hence the attributes belonging to one and the same subject have to be combined wherever that subject is referred to, although they may be expressly stated in one place only.