The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
21. Or this is not so, on account of the difference (of place).
The two secret names do not apply quite equally to the two persons mentioned, because they are connected with different places in the vidyâ. For the clause, 'Its secret name is ahar,' the text exhibits in connexion with the person in the solar orb, while the clause, 'Its secret name is aham,' occurs in connexion with the person in the eye. Now the pronoun 'its' always refers to something mentioned close by; we therefore conclude that the text teaches each secret name as belonging to one special abode of Brahman only. How then can both names be valid for both?--But, an objection is raised, the person within the orb of the sun and the person within the eye are one only; for the text teaches them both to be abodes of the one true Brahman!--True, we reply; but as each secret name is taught only with reference to the one Brahman as conditioned by a particular state, the name applies to Brahman only in so far as it is in that state. We on our part also illustrate the case by a comparison. The teacher always remains the teacher; yet those kinds of services which the pupil has to do to the teacher when sitting have not to be
done when he stands; and vice versa.--The comparison, on the other hand, instituted by the pûrvapakshin is ill chosen, since the duties of the disciple towards his teacher depend on the latter's character as teacher, and that is not changed by his being either in the village or the forest.--Hence the two secret names have to be held apart.