Teachings of Lord Caitanya, Chapter 14: Persons who have been thoroughly cleansed by devotional service and are always joyful, being situated in elevated consciousness, who are very much attached to the studies of Śrīmad-Bhāgavatam, who are always cheerful in the association of devotees, who have accepted the lotus feet of Kṛṣṇa as the ultimate shelter of their lives, and who are pleased to perform all details of devotional service, have in their pure hearts the transcendental ecstasy of attachment. When that ecstatic state of being is enriched with love of Kṛṣṇa and the transcendental experience, one gradually attains to the mature oneness of spiritual life. Such spiritual life is not possible for those who are not situated in Kṛṣṇa consciousness and devotional service. This fact is further corroborated in the Bhakti-rasāmṛta-sindhu wherein it is said: "It is very difficult for the nondevotee to understand the taste of devotional service. Only one who has completely taken shelter of the lotus feet of Kṛṣṇa and whose life is merged in the ocean of devotional service can understand this transcendental pleasure."