Every living being is serving the dictates of desire, anger, lust, illusion, insanity and enviousness - all materially affected. But even while executing such dictations of different temperaments, he is perpetually unhappy
SB Canto 2
Thereafter, the yogī should merge his mind, by his unalloyed intelligence, into the living entity, and then merge the living entity into the Superself. And by doing this, the fully satisfied living entity becomes situated in the supreme stage of satisfaction, so that he ceases from all other activities.
The functions of the mind are thinking, feeling and willing. When the mind is materialistic, or absorbed in material contact, it acts for material advancement of knowledge, destructively ending in discovery of nuclear weapons. But when the mind acts under spiritual urge, it acts wonderfully for going back home, back to Godhead, for life in complete bliss and eternity. Therefore the mind has to be manipulated by good and unalloyed intelligence. Perfect intelligence is to render service unto the Lord. One should be intelligent enough to understand that the living being is, in all circumstances, a servant of the circumstances. Every living being is serving the dictates of desire, anger, lust, illusion, insanity and enviousness—all materially affected. But even while executing such dictations of different temperaments, he is perpetually unhappy. When one actually feels this and turns his intelligence to inquiring about it from the right sources, he gets information of the transcendental loving service of the Lord. Instead of serving materially for the abovementioned different humors of the body, the living entity's intelligence then becomes freed from the unhappy illusion of materialistic temperament, and thus, by unalloyed intelligence, the mind is brought into the service of the Lord. The Lord and His service are identical, being on the absolute plane. Therefore the unalloyed intelligence and the mind are merged into the Lord, and thus the living entity does not remain a seer himself but becomes seen by the Lord transcendentally. When the living entity is directly seen by the Lord, the Lord dictates to him to act according to His desire, and when the living entity follows Him perfectly, the living entity ceases to discharge any other duty for his illusory satisfaction. In his pure unalloyed state, the living being attains the stage of full bliss, labdhopaśānti, and ceases all material hankerings.