Śrīmad-Bhāgavatam 2.4.1
—
Los Angeles, June 24, 197
The body is a combination of five elements. So there is stock in the... This universe is covered by seven layers: earth, water, fire, air, like that. When we shall be going to the spiritual sky, we have to pass through the seven layers. And each layer is ten times bigger than the first. Suppose we pass the air layer; the next layer, the fire, is ten times bigger. Then water, ten times. In this way, we have to pass through. We are so much tightly packed up. It is not so easy that I take a sputnik and go anywhere. No. That requires sādhana-bhajana, practice, how to give up this encagement of seven layers and then completely pure spirit soul, you enter into the spiritual sky. That is merging in the spiritual effulgence. Brahmajyoti. Then you can go further and enter into the spiritual planets, if you are fit for that. Otherwise you'll remain in the brahmajyoti. Nirviśeṣa, without any variety. Simply light. As the jnānīs, they want. But you cannot stay there.