It is confirmed in the Bhagavad-gītā that after many, many births, when one becomes actually wise, he surrenders unto Vāsudeva, knowing perfectly well that Kṛṣṇa (Vāsudeva) is the origin and cause of all causes. Therefore, he sticks to the lotus feet of Kṛṣṇa and gradually develops love for Him. Although such a wise man is very dear to Kṛṣṇa, the others are also accepted as very magnanimous because even though they are distressed or in need of money, they have come to Kṛṣṇa for satisfaction. Thus they are accepted as liberal, broad-minded mahātmās.
Without being elevated to the position of a jñānī, or wise man, no one can stick to the principle of worshiping the Supreme Personality of Godhead. Others who are less intelligent, or those whose intelligence has been taken away by the spell of māyā, are attached to different demigods, on account of the influence of the modes of nature. The wise man is he who has thoroughly understood that he is spirit soul and not simply a body. Because he realizes that he is spirit and that Kṛṣṇa is the supreme spirit, he knows that his intimate relationship should be with Kṛṣṇa, not with this body. The distressed and the man in want of money are in the material concept of life because distress and need of money are both in relationship with this body. One who is inquisitive may be a little above the distressed and the man in need of money, but still he is on the material platform. But a wise man who seeks Kṛṣṇa knows perfectly well that he is spirit soul, or Brahman, and that Kṛṣṇa is the supreme spirit soul, or Param-Brahman. He knows that the spirit soul, being subordinate and finite, should always dovetail himself with the infinite and supreme soul, Kṛṣṇa. That is the relationship of the wise man with Kṛṣṇa.
It can be concluded that a person who is freed from the bodily concept of life is an eligible candidate for pure devotional service. It is also confirmed in the Bhagavad-gītā that after Brahman realization, when one is freed from material anxieties and can see every living entity on an equal level, he is eligible to enter into devotional service.
As has been stated before, there are three kinds of happiness: material, spiritual and devotional. Devotional service and the happiness due to its execution are not possible so long as one is materially affected. If someone has desire for material enjoyment or for becoming one with the supreme, these are both considered material concepts. Because the impersonalists cannot appreciate the spiritual happiness of association and the exchange of loving affairs with the Supreme Personality of Godhead, their ultimate goal is to become one with the Lord. This concept is simply an extension of the material idea. In the material world, everyone is trying to be the topmost head-man amongst all his fellow men or neighbors. Either communally, socially or nationally, everyone is competing to be greater than all others, in the material concept of life. This greatness can be extended to the unlimited, so that one actually wants to become one with the greatest of all, the Supreme Lord. This is also a material concept, although maybe a little more advanced.
However, the perfect spiritual concept of life is complete knowledge of one's constitutional position, and thus one knows enough to dovetail himself in the transcendental loving service to the Lord. One must know that he is finite and that the Lord is infinite. Thus it is not possible to actually become one with the Lord even if one aspires for this. It is simply not possible. Therefore, anyone who has any desire or aspiration for satisfying his senses by becoming more and more important, either in the material sense or in the spiritual sense, cannot actually relish the really sweet taste of devotional service. Śrīla Rūpa Gosvāmī has therefore compared possessing these bhukti (material) and mukti (liberation) desires with being influenced by the black art of a witch: in both cases one is in trouble. Bhukti means material enjoyment, and mukti means to become freed from material anxiety and to become one with the Lord. These desires are compared to being haunted by ghosts and witches, because while these aspirations for material enjoyment or spiritual oneness with the supreme remain, no one can relish the actual transcendental taste of devotional service.