The symptoms of highly developed devotional service for Kṛṣṇa, which are exhibited by the pure devotees, are sometimes imitated by those who are not actually pure devotees. This is described in the Bhakti-rasāmṛta-sindhu. Without devotional service to Kṛṣṇa, such symptoms are artificial, not actual. Sometimes those who are not conversant with the science of devotional service are captivated by the exhibition of such symptoms, but learned devotees know that they are simply imitation.
According to the various divisions and gradations of devotees, permanent devotional attitudes can be divided into five categories: (1) peacefulness, (2) service to Kṛṣṇa, (3) friendship with Kṛṣṇa, (4) parental affection toward Kṛṣṇa, and (5) conjugal love for Kṛṣṇa. Each division has its own taste and relish, and a devotee situated in a particular division is happy in that position. Characteristic symptoms exhibited by a pure devotee are generally laughing and crying; when emotions are favorable, a pure devotee laughs, and when emotions are not favorable, he cries.
(Teachings of Lord Caitanya).

The most intelligent transcendentalist gives up all other processes and engages in the devotional service of the Lord, even though he may have many desires. Through no kind of activity—whether fruitive action or the cultivation of knowledge or the cultivation of mystic yoga—can a person achieve the highest perfection without adding a tinge of devotional service. Except for devotional service, all transcendental processes are just like nipples on the neck of a goat. The nipples on a goat's neck may be squeezed, but they do not supply milk. Therefore if one is to derive actual perfection from his process, he must take to the devotional service of Kṛṣṇa.
In the Bhagavad-gītā (7.16) Lord Kṛṣṇa states:
catur-vidhā bhajante māṁ janāḥ sukṛtino ’rjuna
ārto jijñāsur arthārthī jñānī ca bharatarṣabha
"O best of the Bhâratas, four kinds of people with very righteous backgrounds take up devotional service to Me. They are the distressed, the inquisitive, the seekers of material profit, and the jñānīs, or wise men."
(Teachings of Lord Caitanya).

Persons who cultivate knowledge for liberation are of three kinds: those who simply desire liberation, those who are liberated already, even while in this material existence, and those who are actually self-realized. There are many persons in this world who desire liberation, and sometimes they engage in devotional service for this purpose. It is corroborated in Śrīmad-Bhāgavatam (1.2.26) that those who actually desire liberation give up all kinds of demigod worship and, without envy, concentrate their minds in the worship of Nārāyaṇa, the Supreme Personality of Godhead. When such persons come in contact with a pure devotee, they engage in the devotional service of Kṛṣṇa and give up the idea of liberation. A verse in the Hari-bhakti-sudhodaya states:
aho mahātman bahu-doṣa-duṣṭo
’py ekena bhāty eṣa bhavo guṇena
sat-saṅgamākhyena sukhāvahena
kṛtādya no yena kṛśā mumukṣā ete ’linas
"O great soul, although there are many flaws within this miserable life, there is yet one glory—the association of pure devotees. Cultivate such association. By it our desire for liberation diminishes."
(Teachings of Lord Caitanya).

In Śrīmad-Bhāgavatam (10.14.4) it is clearly said that one who engages in spiritual life to understand things as they are but who lacks all intention of engaging in Kṛṣṇa consciousness simply achieves trouble for his undertaking. There is no substance to his life. Every living entity is part and parcel of the Supreme Lord, and therefore it is the duty of every living entity to serve that supreme whole. Without such service, the living entity falls into material contamination.
Lord Caitanya concluded His teachings to Sanātana Gosvāmī by pointing out that the six kinds of ātmārāmas, or transcendentalists, engage in some kind of devotional service to Kṛṣṇa. In other words, at some time or another all the transcendentalists ultimately come to understand the necessity of rendering devotional service to Kṛṣṇa and become fully Kṛṣṇa conscious. Even if one is very learned or extravagant, he can still engage in the devotional service of the Lord.
The six kinds of transcendentalists are the neophyte transcendentalist, the absorbed transcendentalist, one who is situated in transcendence, one who desires liberation, one who is actually liberated, and one who is engaged in activities in his constitutional position. All of these are ātmārāmas. When a person becomes an ātmārāma, or a great thinker in Kṛṣṇa consciousness, he fully engages in devotional service. According to the grammatical rules, there are many kinds of ātmārāmas, but one sense of the word is sufficient to represent the others. In the collective sense, all the ātmārāmas are inclined to worship the Supreme Lord, Kṛṣṇa.
(Teachings of Lord Caitanya).

At length, Nārada inquired of the hunter-devotee: "Are you getting your foodstuffs regularly?"
"You send so many people," the hunter replied, "and they bring so much food that we cannot eat it all."
"That's all right," Nārada replied. "Whatever you are getting is all right. Now just continue your devotional service in that way."
After Nārada had spoken this, both he and Parvata Muni disappeared from the hunter's home. Lord Caitanya recited this story to show that even a hunter can be engaged in the devotional service of Kṛṣṇa by the influence of pure devotees.
Continuing to explain the ātmārāma verse, Lord Caitanya pointed out that the word ātmā also indicates all varieties of the Personality of Godhead. Generally the Personality of Godhead Himself, Kṛṣṇa, and His different expansions are all known as the Personality of Godhead.
(Teachings of Lord Caitanya).

Thus the Lord gave sixty different meanings to the ātmārāma verse. In addition, He said that ātmā means "any embodied living entity, from the first living creature, Brahmā, down to the ant." He cited a verse from the Sixth Chapter of the Viṣṇu Purāṇa in which it is stated that all the energies of the Lord are spiritual. Although this is the case, the energy which is known as the source of the living entity is called spiritual, but the other energy, which is full of ignorance and is manifested in material activities, is called material nature. Even in the material creation, the living entities are innumerable. If by chance a living entity in the material world can associate with a pure devotee, he can engage in the pure devotional service of Kṛṣṇa. "Formerly I thought of sixty different meanings for the ātmārāma verse," the Lord told Sanātana Gosvāmī, "but here another meaning has come to My mind by your association."
(Teachings of Lord Caitanya).

"A person who constantly engages in devotional service to Kṛṣṇa by chanting His holy name becomes so transcendentally attached to the chanting that his heart becomes softened without extraneous endeavor. When this happens, he exhibits transcendental ecstasies by sometimes laughing, sometimes crying, sometimes singing and sometimes dancing—not exactly in an artistic way, but just like a madman."
Lord Caitanya further informed Prakāśānanda Sarasvatī: "Because I have full faith in My spiritual master's words, I always engage in chanting Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare. I do not know how I have become just like a madman, but I believe the name of Kṛṣṇa has induced Me. I have realized that the transcendental pleasure derived from chanting Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare is just like an ocean, in comparison to which all other pleasures, including the pleasure of impersonal realization, are like the shallow water in canals."
(Teachings of Lord Caitanya).