The System of the Vedanta according to Badarayana's Brahma-Sutras and Cankara's Commentary c8.s7.t2.13

c8.s7.t2.13

4) On account of the precepts as to knowledge and works, which in the absence of personal identity would become invalid; for otherwise deep sleep would mean complete liberation, and what would become then of the works that still remain and have to be atoned for, and of the (lower) knowledge? So too in the case of the other in whose person the soul would have to wake, the continuity of his actions would be destroyed. How can one even assume that any one goes to sleep in the person of A and wakes up in the person of B?— Finally the really liberated might also awake again in that case [for nothing distinguishes him from the others] and liberation would not be definitive. But this is, after Ignorance has once been destroyed, impossible; and from this it follows that God (îçvara), for whom Ignorance is eternally annihilated, cannot awake in the place of the soul.—That is; for the reason that otherwise man would suffer for what he has not committed, and not atone for what he has committed (p. 798, 12), it is impossible to assume that a different person from him who went to sleep wakes up. The comparison with the drop, which cannot be recovered from the body of water, does not agree with the facts; for the distinguishing cause is wanting in this case, but in the case of the soul it is present, namely in the shape of works and knowledge [in which therefore consists the individuality of the individual]. Moreover things which are hard to distinguish for such as we are, are still distinguishable; thus the goose (hansa, for a domestic animal must be meant here) is able to distinguish water and milk when they are mixed (p. 799, 3). “There does not exist an individual “soul different from Brahman, distinguishable from the Existent “like a drop of water from a body of water; but the Existent “itself is, in consequence of the connection with the Upâdhis, “termed individual soul in a metaphorical sense, as we have “often set forth; and therefore the matter stands thus: the “action of a given individual soul extends so far as the connection with a given Upādhi-complex exists, and where another Upādhi is present, we have the action of another individual soul; but one and the same Upādhi is in deep sleep and the waking state in the position of the seed and the plant; therefore it is the same soul which wakes up again.”