Without being elevated to the position of a jñānī, or wise man, one cannot stick to the principle of worshiping the Supreme Personality of Godhead. The 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 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 Para-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 stated before, there are three kinds of happiness-material, spiritual and devotional. Devotional service and the happiness due to its execution are not possible as 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 among 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.