In the Brahma-saṁhitā it is said that the Supreme Absolute Truth, Govinda, the Personality of Godhead, although one without a second, is infallibly expanded by innumerable forms nondifferent from one another, and although He is the original person, He is still ever young with permanent youthful energy. He is very difficult to know simply by learning the transcendental science of the Vedas, but He is very easily realized by His pure devotees.
The expansions of different forms of the Lord, as from Kṛṣṇa to Baladeva to Saṅkarṣaṇa, from Saṅkarṣaṇa to Vāsudeva, from Vāsudeva to Aniruddha, from Aniruddha to Pradyumna and then again to second Saṅkarṣaṇa and from Him to the Nārāyaṇa puruṣāvatāras, and innumerable other forms, which are compared to the constant flowing of the uncountable waves of a river, are all one and the same. They are like lamps of equal power which kindle from one lamp to another. That is the transcendental potency of the Lord. The Vedas say that He is so complete that even though the whole complete identity emanates from Him, He still remains the same complete whole (pūrṇasya pūrṇam ādāya pūrṇam evāvaśiṣyate (Śrī Īśopaniṣad, Invocation)). As such, there is no validity in a material conception of the Lord produced by the mental speculator. Thus He remains always a mystery for the mundane scholar, even if he is vastly learned in the Vedic literatures (vedeṣu durlabham adurlabham ātma-bhaktau (BS 5.33)). Therefore, the Lord is beyond the limit of conception for mundane learned scholars, philosophers or scientists. He is easily understandable for the pure devotee because the Lord declares in the Bhagavad-gītā (BG 18.54) that after surpassing the stage of knowledge, when one is able to be engaged in the devotional service of the Lord, then only can one know the true nature of the Lord. One cannot have any clear conception of the Lord or His holy name, form, attributes, pastimes, etc., unless one is engaged in His transcendental loving service. The statement of the Bhagavad-gītā that one must first of all surrender unto the Lord, being freed from all other engagements, means that one must become a pure, unconditional devotee of the Lord. Only then can one know Him by the strength of devotional service.
Mahārāja Parīkṣit admitted in the previous verse that the Lord is inconceivable even for the greatest learned scholars. Why then should he again request Śukadeva Gosvāmī to clarify his insufficient knowledge about the Lord? The reason is clear. Not only was Śukadeva Gosvāmī vastly learned in the Vedic literatures, but he was also a great self-realized soul and a powerful devotee of the Lord. A powerful devotee of the Lord is, by the grace of the Lord, more than the Lord Himself. The Personality of Godhead Śrī Rāmacandra attempted to bridge the Indian Ocean to reach the island of Laṅkā, but Śrī Hanumānjī, the unalloyed devotee of the Personality of Godhead, could cross the ocean simply by jumping over it. The Lord is so merciful upon His pure devotee that He presents His beloved devotee as more powerful than Himself. The Lord expressed Himself to be unable to save Durvāsā Muni, although the Muni was so powerful that he could reach the Lord directly under material conditions. But Durvāsā Muni was saved by Mahārāja Ambarīṣa, a devotee of the Lord. Therefore, not only is a devotee of the Lord more powerful than the Lord, but also worship of the devotee is considered more effective than direct worship of the Lord (mad-bhakta-pūjābhyadhikā (SB 11.19.21)).
The conclusion is, therefore, that a serious devotee must first approach a spiritual master who not only is well versed in the Vedic literatures but is also a great devotee with factual realization of the Lord and His different energies. Without the help of such a devotee spiritual master, one cannot make progress in the transcendental science of the Lord. And a bona fide spiritual master like Śukadeva Gosvāmī does not speak about the Lord only in the matter of His internal potencies, but also explains how He associates with His external potencies.
The Lord's pastimes in the internal potency are displayed in His activities in Vṛndāvana, but His external potential works are directed in His features of Kāraṇārṇavaśāyī Viṣṇu, Garbhodakaśāyī Viṣṇu and Kṣīrodakaśāyī Viṣṇu. Śrīla Viśvanātha Cakravartī offers his good counsel to the interested Vaiṣṇavas when he says that they should not be interested in hearing only about the Lord's activities (like rāsa-līlā), but must be keenly interested in His pastimes in His features of the puruṣāvatāras in connection with sṛṣṭi-tattva, creational functions, following the examples of Mahārāja Parīkṣit, the ideal disciple, and Śukadeva Gosvāmī, the ideal spiritual master.