The mental concoctions of happiness and distress in this material world are compared to dreams because of their falseness
SB Canto 7
It is fruitless to see and talk of the material modes of nature and their resultant so-called happiness and distress as if they were factual. When the mind wanders during the day and a man begins to think himself extremely important, or when he dreams at night and sees a beautiful woman enjoying with him, these are merely false dreams. Similarly, the happiness and distress caused by the material senses should be understood to be meaningless.
The happiness and distress derived from the activities of the material senses are not actual happiness and distress. Therefore Bhagavad-gītā speaks of happiness that is transcendental to the material conception of life (sukham ātyantikaṁ yat tad buddhi-grāhyam atīndriyam (BG 6.21)). When our senses are purified of material contamination, they become atīndriya, transcendental senses, and when the transcendental senses are engaged in the service of the master of the senses, Hṛṣīkeśa, one can derive real transcendental pleasure. Whatever distress or happiness we manufacture by mental concoction through the subtle mind has no reality, but is simply a mental concoction. One should therefore not imagine so-called happiness through mental concoction. Rather, the best course is to engage the mind in the service of the Lord, Hṛṣīkeśa, and thus feel real blissful life.
There is a Vedic statement apāma-somam amṛtā abhūma apsarobhir viharāma. With reference to such a conception, one wants to go to the heavenly planets to enjoy with the young girls there and drink soma-rasa. Such imaginary pleasure, however, has no value. As confirmed in Bhagavad-gītā (7.23), antavat tu phalaṁ teṣāṁ tad bhavaty alpa-medhasām: "Men of small intelligence worship the demigods, and their fruits are limited and temporary." Even if by fruitive activity or worship of the demigods one is elevated to the higher planetary systems for sense enjoyment, his situation is condemned in Bhagavad-gītā as antavat, perishable. The happiness one enjoys in this way is like the pleasure of embracing a young woman in a dream; for some time it may be pleasing, but actually the basic principle is false. The mental concoctions of happiness and distress in this material world are compared to dreams because of their falseness. All thoughts of obtaining happiness by using the material senses have a false background and therefore have no meaning.