CC Ādi 1.47
antaryāmī, bhakta-śreṣṭha, — ei dui rūpa
Śrīla Kṛṣṇadāsa Kavirāja Gosvāmī states that the instructing spiritual master is a bona fide representative of Śrī Kṛṣṇa. Śrī Kṛṣṇa Himself teaches us as the instructing spiritual master from within and without. From within He teaches as Paramātmā, our constant companion, and from without He teaches from the Bhagavad-gītā as the instructing spiritual master. There are two kinds of instructing spiritual masters. One is the liberated person fully absorbed in meditation in devotional service, and the other is he who invokes the disciple’s spiritual consciousness by means of relevant instructions. Thus the instructions in the science of devotion are differentiated in terms of the objective and subjective ways of understanding. The ācārya in the true sense of the term, who is authorized to deliver Kṛṣṇa, enriches the disciple with full spiritual knowledge and thus awakens him to the activities of devotional service.
When by learning from the self-realized spiritual master one actually engages himself in the service of Lord Viṣṇu, functional devotional service begins. The procedures of this devotional service are known as abhidheya, or actions one is dutybound to perform. Our only shelter is the Supreme Lord, and one who teaches how to approach Kṛṣṇa is the functioning form of the Personality of Godhead. There is no difference between the shelter-giving Supreme Lord and the initiating and instructing spiritual masters. If one foolishly discriminates between them, he commits an offense in the discharge of devotional service.
Śrīla Sanātana Gosvāmī is the ideal spiritual master, for he delivers one the shelter of the lotus feet of Madana-mohana. Even though one may be unable to travel on the field of Vṛndāvana due to forgetfulness of his relationship with the Supreme Personality of Godhead, he can get an adequate opportunity to stay in Vṛndāvana and derive all spiritual benefits by the mercy of Sanātana Gosvāmī. Śrī Govindajī acts exactly like the śikṣā-guru (instructing spiritual master) by teaching Arjuna the Bhagavad-gītā. He is the original preceptor, for He gives us instructions and an opportunity to serve Him. The initiating spiritual master is a personal manifestation of Śrīla Madana-mohana vigraha, whereas the instructing spiritual master is a personal representative of Śrīla Govindadeva vigraha. Both of these Deities are worshiped at Vṛndāvana. Śrīla Gopīnātha is the ultimate attraction in spiritual realization.