When Lord Brahma completes the one hundred celestial years of his life, Lord Siva again performs this duty of destruction. At that time all the spirit souls enter into the body of Karanodakasayi Visnu or Maha Visnu. At the end of each day of Lord Brahma, all souls enter Garbhodakasayi Visnu, and at the end of Brahma’s life, even the millions of manifestations of Garbhodakasayi Visnu enter Karanodakasayi Visnu along with the spirit souls. At the time of creation, Karanodakasayi Visnu generates innumerable manifestations of Garbhodakasayi Visnu, and at the time of complete annihilation, they enter back into his body.