I need help understanding the following passage:

Question

“Could we suppose two distinct
incommunicable consciousnesses acting in the same body, the one constantly by day, the other by night; and, on
the other side, the same consciousness, acting by intervals, in two distinct bodies?” (399) If we go by Locke’s
definition, it is clear that in the first case the day and night man would indeed be two distinct persons, as different
from one another as Socrates and Plato. And in the second case, there would be one person in two bodies just
as it would be the same person wearing two different sets of clothing. Locke notes that this being the same
distinct consciousness is in no way dependent on it residing in the same immaterial substance, as personal identity
would be determined by consciousness whether or not it were annexed to such a substance. “For, granting that
the thinking substance in man must be necessarily supposed immaterial, it is evident that [that] immaterial thinking
thing may sometimes part with its past consciousness and be restored to it again….Make these intervals of
memory and forgetfulness to take their turns regularly by day and night and you have two persons with the same
immaterial spirit, as much as in the former instance of two persons with the same body” (399). Anything a
substance has thought or done that a person cannot recollect through consciousness does not belong to that
person any more than the thoughts or actions of another person altogether.