In the Śrīmad-Bhāgavatam it is said that the foolish do not know that Viṣṇu is the ultimate goal of life. According to the conclusion of all authoritative Vedic scriptures, when a person comes to the stage of appreciating Viṣṇu, he is at the beginning of devotional service. If one cultivates devotional service further and further, under proper guidance, other features of devotional service will gradually become manifest. At this stage of śānta-rasa, one can see Lord Viṣṇu, the Supreme Personality of Godhead, the deliverer of even the demons. The Lord is appreciated by such would-be devotees as the eternal transcendental form, chief of all self-realized souls, the supersoul, the supreme Brahman, completely pacified, completely controlled and pure, merciful to the devotees and untouched by any material condition. This appreciation of Lord Viṣṇu in awe and veneration by the saintly is to be understood as the sign that they are situated in the śānta-rasa, or neutral stage of devotional service.
This stage of śānta-rasa can be attained by the impersonalists only when they are in association with pure devotees. Otherwise it is not possible. After Brahman realization, when a liberated soul comes in contact with a pure devotee of Lord Kṛṣṇa and submissively accepts the teachings of Lord Kṛṣṇa without misinterpretation, he becomes situated in this neutral stage of devotional service. The best example of saintly persons situated in the śānta-rasa are Sanaka, Sanātana, Sananda, and Sanat-kumāra, the Kumāra brothers. These four saintly persons (known as Catuḥsana) were sons of Lord Brahmā. After their birth, when they were ordered by their father to become householders and increase human society, they refused the order. They said that they had already decided not to become entangled with family life; they would rather live as saintly brahmacārīs for their own perfection. So these great saints have been living for millions of years now, but still they appear to be just like boys of four or five years. Their complexions are very fair, there is an effulgence in their bodies, and they always travel naked. These four saintly persons almost always remain together.
In one of the prayers of the Kumāra brothers, the declaration is made: "My Lord Mukunda (Kṛṣṇa, the giver of liberation), only so long as one does not happen to see Your eternal form of bliss and knowledge, appearing just like a newly-grown tāmala tree, with a bluish hue—only for so long can the impersonal feature of the absolute truth, known as Brahman, be very pleasing to a saintly person."
The qualifications of a saintly person are described in the Bhakti-rasāmṛta-sindhu as follows: A saintly person is one who understands fully that simply by discharging devotional service he can become confident of liberation. He is always situated in the regulative principles of devotional life and at the same time aspires to be liberated from the material entanglement.
A saintly person thinks like this: "When shall I be able to live alone in the caves of the mountains? When shall I be dressed simply with undergarments? When shall I be satisfied by eating simply a little fruit and vegetables? When will it be possible for me to always think of the lotus feet of Mukunda, who is the source of the Brahman effulgence? When, in such a spiritual condition of life, shall I fully understand my days and nights to be insignificant moments in eternal time?"
The devotees and self-realized persons who are engaged in preaching the glories of the Lord always maintain an ecstatic love for the Lord within their hearts. Thus they are benefitted by the rays of the ecstatic moon, and they are called saintly persons.