The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
18. For this very reason (there are applied to Brahman) comparisons such as that of the images of the sun and the like.
Because that Self is of the nature of intelligence, devoid of all difference, transcending speech and mind, to be
described only by denying of it all other characteristics, therefore the Moksha Sâstras compare it to the images of the sun reflected in the water and the like, meaning thereby that all difference in Brahman is unreal, only due to its limiting conditions. Compare, e.g. out of many, the two following passages: 'As the one luminous sun when entering into relation to many different waters is himself rendered multiform by his limiting adjuncts; so also the one divine unborn Self;' and 'The one Self of all beings separately abides in all the individual beings; hence it appears one and many at the same time, just as the one moon is multiplied by its reflections in the water.'
The next Sûtra raises an objection.