There are two kinds of dissolution. One is when Brahma goes to sleep, and another is when Brahma dies. When Brahma goes to sleep, the highest planetary system does not dissolve, the lower planetary systems, beginning from heavenly planets downwards, everything is dissolved. And when the day comes out, they are again created. When the living entities enter into Brahma, or into the Body of Narayana, they keep their own spiritual body, that is very small, 1/10,000 of tip of hair, and when there is again material creation, they manifest again with different kinds of body.
Letter to Aniruddha, 9 April, 1968