The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut [1896] at sacred-texts.com
2. And some (state the Self to be) the shaper (creator); sons and so on (being the lovely things which he shapes).
Moreover the members of one sâkhâ state that the Self is, in that intermediate state, the shaper of lovely things, 'He, the person who is awake in us while we are asleep, shaping one lovely thing after another' (Ka. Up. II, 5, 8).
[paragraph continues] Kâma (lovely things) in this passage means sons, &c., that are so called because they are beloved.--But may not the term 'kâmâh' denote desires merely?--No, we reply; the word kâma is here used with reference to sons, &c.; for those form the general subject of discussion, as we see from some preceding passages, 'Choose sons and grandsons,' &c., and 'I make thee the enjoyer of all kâmas' (Ka. Up. I, 1, 23; 24).--And that that shaper is the highest Self (prâgña) we infer from the general subject-matter and from the complementary sentence. That the highest Self is the general subject-matter appears from II, 14, 'That which thou seest as neither this nor that.' And to that highest Self there also refers the complementary sentence II, 5, 8, 'That indeed is the Bright, that is Brahman, that alone is called the Immortal. All worlds are contained in it, and no one goes beyond.'--Now it is admitted that the world (creation) of our waking state of which the highest Self (prâgña) is the maker is real; hence the world of our dreaming state must likewise be real. That the same reasoning applies to the waking and the sleeping state a scriptural passage also declares, 'Here they say: No, this is the same as the place of waking, for what he sees while awake the same he sees while asleep' (Bri. Up. IV, 3, 14).--Hence the world of dreams is real.--To this we reply as follows.