"Only unto those great souls who have implicit faith in both the Lord and the spiritual master are all the imports of the Vedic knowledge automatically revealed." (Śvetāśvatara Upaniṣad 6.23) It is further stated, tuṣyeyaṁ sarva-bhūtātmā guru-śuśrūṣayā and taranty añjo bhavārṇavam. Simply by rendering service to the spiritual master, one crosses the ocean of nescience and returns home, back to Godhead. Thus he gradually sees the Supreme Lord face to face and enjoys life in association with the Lord. The ultimate goal of yoga is to come in contact with the Supreme Personality of Godhead. Unless this point is achieved, one's so-called yoga practice is simply labor without any benefit.
(Srimad Bhagavatam-----7:15:28-----purport).

Therefore it is said, the Lord's vigilance is never diminished. This is also confirmed in Bhagavad-gītā (15.15). Sarvasya cāhaṁ hṛdi sanniviṣṭo mattaḥ smṛtir jñānam apohanaṁ ca: the Supreme Personality of Godhead in His Paramātmā feature is always present within the hearts of all living entities, and from Him come memory, knowledge and forgetfulness. This is also indicated in this verse by the word suparṇam, which means "friend." In the Śvetāśvatara Upaniṣad (4.6) it is therefore said, dvā suparṇa-sayujā sakhāyā samānaṁ vṛkṣaṁ pariṣasvajāte: two birds are sitting on the same tree as friends. One bird is eating the fruit of the tree, and the other is simply observing. This observing bird is always present as a friend to the eating bird and giving him remembrance of things he wanted to do. Thus if we take into account the Supreme Personality of Godhead in our daily affairs, we can see Him or at least perceive His presence everywhere.
(Srimad Bhagavatam-----8:1:11-----purport).

Parāsya śaktir vividhaiva śrūyate (Śvetāśvatara Upaniṣad 6.8 (Cc. Madhya 13.65, purport)). In the Vedas it is said that the potencies of the Supreme Personality of Godhead are called by different names, such as yogamāyā and mahāmāyā. Ultimately, however, the Lord's potency is one, exactly as electric potency is one although it can act both to cool and to heat. The Lord's potency acts in both the spiritual and material worlds. In the spiritual world the Lord's potency works as yogamāyā, and in the material world the same potency works as mahāmāyā, exactly as electricity works in both a heater and a cooler. In the material world, this potency, working as mahāmāyā, acts upon the conditioned souls to deprive them more and more of devotional service.
(Srimad Bhagavatam-----10:1:25-----purport).

Devotees, therefore, following in the footsteps of Lord Brahmā, pray, govindam ādi-puruṣaṁ tam ahaṁ bhajāmi **, worshiping the ādi-puruṣa, the supreme truth, Govinda. Everything, everywhere, is performed in terms of three principles, jñāna-bala-kriyā—knowledge, strength and activity. In every field, if there is not full knowledge, full strength and full activity, an endeavor is never successful. Therefore, if one wants success in everything, one must be backed by these three principles. In the Vedas (Śvetāśvatara Upaniṣad 6.8) there is this statement about the Supreme Personality of Godhead:
na tasya kāryaṁ karaṇaṁ ca vidyate
na tat samaś cābhyadhikaś ca dṛśyate
parāsya śaktir vividhaiva śrūyate
svābhāvikī jñāna-bala-kriyā ca
(Cc. Madhya 13.65, purport)
The Supreme Personality of Godhead does not need to do anything personally, for He has such potencies that anything He wants done will be done perfectly well through the control of material nature (svābhāvikī jñāna-bala-kriyā ca). Similarly, those who are engaged in the service of the Lord are not meant to struggle for existence.
(Srimad Bhagavatam-----10:2:26-----purport).

"The Supreme Lord has nothing to do, and no one is found to be equal to or greater than Him, for everything is done naturally and systematically by His multifarious energies." (Śvetāśvatara Upaniṣad 6.8) Creation, maintenance and annihilation are all conducted personally by the Supreme Personality of Godhead, and this is confirmed in Bhagavad-gītā (mayādhyakṣeṇa prakṛtiḥ sūyate sa-carācaram (B.G.9:10). Yet ultimately the Lord does not need to do anything, and therefore He is nirvikāra, changeless. Because everything is done under His direction, He is called sṛṣṭi-kartā, the master of creation. Similarly, He is the master of annihilation. When a master sits in one place while his servants work in different duties, whatever the servants are doing is ultimately an activity of the master, although he is doing nothing (na tasya kāryaṁ karaṇaṁ ca vidyate). The Lord's potencies are so numerous that everything is nicely done. Therefore, He is naturally still and is not directly the doer of anything in this material world.
(Srimad Bhagavatam-----10:3:19-----purport).

Kṛṣṇa has many potencies: parāsya śaktir vividhaiva śrūyate (Śvetāśvatara Upaniṣad 6.8 (Cc. Madhya 13.65, purport)). The description of Aghāsura was disclosed after one year. Some act of Kṛṣṇa's potency must have been involved. Therefore Mahārāja Parīkṣit was very curious to know about this, and he requested Śukadeva Gosvāmī to explain it.
(Srimad Bhagavatam-----10:12:42-----purport).

The Vedas (Śvetāśvatara Upaniṣad 6.8) assert that the Supreme Personality of Godhead has nothing to do personally (na tasya kāryaṁ karaṇaṁ ca vidyate) because He is doing everything through His energies and potencies (parāsya śaktir vividhaiva śrūyate (Cc. Madhya 13.65, purport)). Nonetheless, here we see that He took personal care to find the calves of His friends. This was Kṛṣṇa's causeless mercy. Mayādhyakṣeṇa prakṛtiḥ sūyate sa-carācaram: (B.G.9:10) all the affairs of the entire world and the entire cosmic manifestation are working under His direction, through His different energies. Still, when there is a need to take care of His friends, He does this personally. Kṛṣṇa assured His friends, "Don't be afraid. I am going personally to search for your calves." This was Kṛṣṇa's causeless mercy.
(Srimad Bhagavatam-----10:13:14-----purport).

One description given of Brahman is satyaṁ brahma, ānanda-rūpam: "Brahman is the Absolute Truth and complete ānanda, or bliss." The forms of Viṣṇu, the Supreme Brahman, were one, but They were manifested differently. The followers of the Upaniṣads, however, cannot understand the varieties manifested by Brahman. This proves that Brahman and Paramātmā can actually he understood only through devotion, as confirmed by the Lord Himself in Śrīmad-Bhāgavatam: bhaktyāham ekayā grāhyaḥ (S.B.11:14:21). To establish that Brahman indeed has transcendental form, Śrīla Viśvanātha Cakravartī Ṭhākura gives various quotations from the śāstras. In the Śvetāśvatara Upaniṣad (3.8), the Supreme is described as āditya-varṇaṁ tamasaḥ parastāt, "He whose self-manifest form is luminous like the sun and transcendental to the darkness of ignorance."
(Srimad Bhagavatam-----10:13:54-----purport).

Kṛṣṇa's energy—His māyā-śakti, or svarūpa-śakti—is one, but it is manifested in varieties. parāsya śaktir vividhaiva śrūyate (Śvetāśvatara Upaniṣad 6.8 (Cc. Madhya 13.65, purport)). The difference between Vaiṣṇavas and Māyāvādīs is that Māyāvādīs say that this māyā is one, whereas Vaiṣṇavas recognize its varieties. There is unity in variety. For example, in one tree, there are varieties of leaves, fruits and flowers. Varieties of energy are required for performing the varieties of activity within the creation. To give another example, in a machine all the parts may be iron, but the machine includes varied activities. Although the whole machine is iron, one part works in one way, and other parts work in other ways.
(Srimad Bhagavatam-----10:13:57-----purport).

(1) From the Caitanya Upaniṣad (5): gauraḥ sarvātmā mahā-puruṣo mahātmā mahā-yogī tri-guṇātītaḥ sattva-rūpo bhaktiṁ loke kāśyati. "Lord Gaura, who is the all-pervading Supersoul, the Supreme Personality of Godhead, appears as a great saint and powerful mystic who is above the three modes of nature and is the emblem of transcendental activity. He disseminates the cult of devotion throughout the world."
(2) From the Śvetāśvatara Upaniṣad (6.7 and 3.12):
tam īśvarāṇāṁ paramaṁ maheśvaraṁ
taṁ devatānāṁ paramaṁ ca daivatam
patiṁ patīnāṁ paramaṁ parastād
vidāma devaṁ bhuvaneśam īḍyam
"O Supreme Lord, You are the Supreme Maheśvara, the worshipable Deity of all the demigods and the Supreme Lord of all lords. You are the controller of all controllers, the Personality of Godhead, the Lord of everything worshipable."
(Sri Caitanya Caritamrta-----1:2:22-----purport).

The internal potency of the Lord, which is called cit-śakti or antaraṅga-śakti, exhibits variegatedness in the transcendental Vaikuṇṭha cosmos. Besides ourselves, there are unlimited numbers of liberated living beings who associate with the Personality of Godhead in His innumerable features. The material cosmos displays the external energy, in which the conditioned living beings are provided all liberty to go back to the Personality of Godhead after leaving the material tabernacle. The Śvetāśvatara Upaniṣad (6.8) informs us:
na tasya kāryaṁ karaṇaṁ ca vidyate
na tat-samaś cābhyadhikaś ca dṛśyate
parāsya śaktir vividhaiva śrūyate
svābhāvikī jñāna-bala-kriyā ca
(Cc. Madhya 13.65, purport)
"The Supreme Lord is one without a second. He has nothing to do personally, nor does He have material senses. No one is equal to Him or greater than Him. He has unlimited, variegated potencies of different names, which exist within Him as autonomous attributes and provide Him full knowledge, power and pastimes."
(Sri Caitanya Caritamrta-----1:2:103-----purport).

One who is not taught by a bona fide spiritual master cannot understand the Vedic literature. To emphasize this point, Lord Kṛṣṇa, while instructing Arjuna, clearly said that it was because Arjuna was His devotee and confidential friend that he could understand the mystery of the Bhagavad-gītā. It is to be concluded, therefore, that one who wants to understand the mystery of revealed scriptures must approach a bona fide spiritual master, hear from him very submissively and render service to him. Then the import of the scriptures will be revealed. It is stated in the Vedas (Śvetāśvatara Up. 6.23):
yasya deve parā bhaktir yathā deve tathā gurau
tasyaite kathitā hy arthā prakāśante mahātmanaḥ
(ŚU 6.23)
"The real import of the scriptures is revealed to one who has unflinching faith in both the Supreme Personality of Godhead and the spiritual master." Śrīla Narottama dāsa Ṭhākura advises, sādhu-śāstra-guru-vākya, hṛdaye kariyā aikya
(Sri Caitanya Caritamrta-----1:7:48-----purport).

A person who cannot keep his faith in the words of his spiritual master but acts independently never receives the authority to chant the holy name of the Lord. It is said in the Vedas (Śvetāśvatara Up. 6.23):
yasya deve parā bhaktir yathā deve tathā gurau
tasyaite kathitā hy arthāḥ prakāśante mahātmanaḥ
(ŚU 6.23)
"Only unto those great souls who have implicit faith in both the Lord and the spiritual master are all the imports of Vedic knowledge automatically revealed." This Vedic injunction is very important, and Śrī Caitanya Mahāprabhu supported it by His personal behavior. Believing in the words of His spiritual master, He introduced the saṅkīrtana movement, just as the present Kṛṣṇa consciousness movement was started with belief in the words of our spiritual master.
(Sri Caitanya Caritamrta-----1:7:95-96-----purport).