SB 5.13.7
surair hrta-svah kva ca nirvinna-cetah
socan vimuhyann upayati kasmalam
kvacic ca gandharva-puram pravistah
pramodate nirvrtavan muhurtam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sometimes, being defeated or plundered by a superior, powerful agent, a living entity loses all his possessions. He then becomes very morose, and lamenting their loss, he sometimes becomes unconscious. Sometimes he imagines a great palatial city in which he desires to live happily with his family members and riches. He thinks himself fully satisfied if this is possible, but such so-called happiness continues only for a moment.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The word gandharva-puram is very significant in this verse. Sometimes in the forest a very big castle appears, and this is called a castle in the air. Actually this castle does not exist anywhere but in one’s imagination. This is called gandharva-pura. In the material forest, the conditioned soul sometimes contemplates great castles and skyscrapers, and he wastes his energy for such things, hoping to live in them very peacefully with his family forever. However, the laws of nature do not allow this. When he enters such castles, he temporarily thinks that he is very happy, even though his happiness is impermanent. His happiness may last for a few years, but because the owner of the castle has to leave the castle at the time of death, everything is eventually lost. This is the way of worldly transactions. Such happiness is described by Vidyapati as the happiness one derives upon seeing a drop of water in the desert. The desert is heated by scorching sunshine, and if we want to reduce the desert temperature, we need huge amounts of water — millions and millions of gallons. What effect will one drop have? Water certainly has value, but one drop of water cannot reduce the heat of the desert. In this material world everyone is ambitious, but the heat is very scorching. What will an imaginary castle in the air do to help? Srila Vidyapati has therefore sung: tatala saikate, vari-bindu-sama, suta-mita-ramani-samaje. The happiness of family life, friends and society is compared to a drop of water in the scorching desert. The entire material world is busy trying to attain happiness because happiness is the prerogative of the living being. Unfortunately, due to falling in contact with the material world, the living entity simply struggles for existence. Even if one becomes happy for a while, a very powerful enemy may plunder everything. There are many instances in which big businessmen suddenly become paupers in the street. Yet the nature of material existence is such that foolish people are attracted to these transactions and they forget the real business of self-realization.