Prabhupāda: This duration of Brahmā, the, the material manifestation in the lower status, this planetary system, when Brahmā days is finished, all these planetary systems becomes covered in water. There is devastation, devastation, and when again Brahmā, the supreme person in the Brahmaloka, he rises up, then again creation begins. That is the law of creation. So avyaktād vyaktayaḥ sarvāḥ prabhavanty ahar-āgame. Ahaḥ. Ahaḥ means in the daytime. When there is daytime, daytime, twelve hours, then this material manifestation, what you see, all these planets, they are manifested, seen. But when there is nighttime, all these planetary system becomes merged into devastation of water. So rātry-āgame pralīyante tatraiva avyakta-saṁjñake. Rātry-āgame means when the night is there, then again all these planets become invisible. They are devastated within the water. This is the nature of this material world. Bhūta-grāmaḥ sa evāyaṁ bhūtvā bhūtvā pralīyate (BG 8.19). So because the whole planetary system becomes, I mean to say, merged into devastation of water, therefore all living entities, they, at that time, pralaya, devastation, they all die. Bhūta-grāmaḥ sa evāyaṁ bhūtvā bhūtvā pralīyate (BG 8.19).
So this nature is going on. When it is a daytime they are again coming out, and when there is nighttime they again all becomes merged into this water. Rātry-āgame avaśaḥ pārtha, prabhavaty ahar-āgame. Avaśaḥ. Avaśaḥ means, although they do not like devastation, the devastation will come and, I mean to say, overflood all this. And again, when the day also comes, again gradually the waters will disappear. Just like in this planet the three-fourth is covered with water, and gradually land is coming out. It takes times. And one day it will come when there will be no water, simply land. There will be no water. That is the process of nature. Paras tasmāt tu bhāvo 'nyaḥ. Paras tasmāt tu bhāvaḥ anyaḥ avyakto 'vyaktāt sanātanaḥ: (BG 8.20) "But My dear Arjuna, beyond this place of 'sometimes it is appearing, sometimes it is disappearing,' beyond this, there is another nature." Just take this information from Bhagavad-gītā. We cannot calculate what is the length and breadth of this universe, but there are millions and millions of universes like this within this material world. And above this material world there is another sky, which is called spiritual sky. And in that sky the planets are all eternal. And there life is eternal also.
This manifestation, this material manifestation, is only three-fourth part of the whole manifestation, both spiritual and material. You'll find in the Bhagavad-gītā, ekāṁśena sthito jagat (BG 10.42). Ekāṁśa means one-fourth part. These manifestations are one-fourth part. And three-fourth part manifestation is beyond this material sky. This material sky is covered. The... When you see to the sky you'll find that ball-like covering. That is the covering. So millions and millions of miles, the covering is there. And after penetrating that covering, you can enter into the spiritual sky. That is open sky.