Therefore, in the Bhagavad-gītā it is said, ūrdhva-mūlam adhah-śākham [Bg. 15.1]. You have... You know. Just like a tree, standing on the shore of a reservoir of water. You'll find the reflection of the tree downward. Everything is topsy-turvied. The trunk, the root is on the up, and the foliage, which is on the up, that has come down. Similarly, this material world is described in the Bhagavad-gītā, Fifteenth Chapter: ūrdhva-mūlam adhah-śākham. Generally, we see tree downwards, root, but in the reflection you will find the roots upward. Therefore ūrdhva-mūlam adhah-śākham means these material varieties are simply an imitation of the original variety. Just like I'll give you very nice example. Just there will be a great fair.
Just like we had in this Allahabad, Māgha-melā. So because government knew that many people will come to take bath in the Ganges, confluence of Ganges and Yamunā, all of a sudden, a great city, practically, was developed. Those who have seen—so many houses, camps, electric lights, post office, everything. Temporary, created. But as soon as... It is maintained also so long the melā, the fair, is going on. And as soon as the duration of melā is finished, all people go away and the temporary township is also demolished. That we have seen. Similarly, this material world means it is a kind of fair, assembly of so many men. What is the purpose? The purpose is to give them chance, just the Māgha-melā is a chance to become purified, to become pious. They take bath in the Ganges. They become, get an opportunity, an auspicious moment to take bath.
Prabhupada's lecture - Śrīmad-Bhāgavatam 1.2.23 - Los Angeles, August 26, 1972