The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
9. But on account of its proximity (to the higher Brahman) there is designation (of the lower Brahman) as that.
The word 'but' indicates the setting aside of the doubt.--As the lower Brahman is in proximity to the higher one, there is nothing unreasonable in the word 'Brahman' being applied to the former also. For when the higher Brahman is, for the purposes of pious meditation, described as possessing certain effected qualities--such as consisting of mind and the rest--which qualities depend on its connexion with certain pure limiting adjuncts; then it is what we call the lower Brahman.--But with the assumption of the lower Brahman there does not agree what scripture says about the souls not returning; for there is no permanence anywhere apart from the highest Brahman. And scripture declares that those who have set out on the road of the gods do not return, 'They who proceed on that path do not return to the life of man' (Kh. Up. IV, 15, 6); 'For them there is no return here' (Bri. Up. VI, 2, 15); 'Moving upwards by that a man reaches immortality' (Kh. Up. VIII, 6, 5).
To this objection we make the following reply.