Krsna, the Supreme Personality of Godhead, explaining the method of His appearance and disappearance. People do not know it. Just like the sun. Because we do not see at night, formerly some people used to think "The sun is now dead, or gone." But later on, by scientific method, they have come to know the sun is always in the sky. Due to our different position, we do not see the sun at night. Otherwise, the sun is there. If this is possible for an ordinary material thing, how much it is greatly possible for the Supreme Spirit.
Lecture on Bhagavad-gita 4.6, Bombay, March 26, 1974