The Supreme Personality of Godhead has three kinds of internal potency, namely the hlādinī-śakti, or pleasure potency, the sandhinī-śakti, or existential potency, and the samvit-śakti, or cognitive potency. In the Viṣṇu Purāṇa (1.12.69) the Lord is addressed as follows: "O Lord, You are the support of everything. The three attributes hlādinī, sandhinīand samvit exist in You as one spiritual energy. But the material modes, which cause happiness, misery and mixtures of the two, do not exist in You, for You have no material qualities."
(Sri Caitanya Caritamrta----1:4:60----purport).

Out of the total manifestations of the sandhinī energy of the Lord, one fourth is displayed in the material world, and three fourths are displayed in the spiritual world. The Lord's energy is divided into three component parts, namely sandhinī, saṁvit and hlādinī; in other words, He is the full manifestation of existence, knowledge and bliss. In the material world such a sense of existence, knowledge and pleasure is meagerly exhibited, and all living entities, who are minute parts and parcels of the Lord, are eligible to relish such consciousness of existence, knowledge and bliss very minutely in the liberated stage, whereas in the conditioned stage of material existence they can hardly appreciate what is the factual, existential, cognizable and pure happiness of life. The liberated souls, who exist in far greater numerical strength than those souls in the material world, can factually experience the potency of the above-mentionedsandhinī, saṁvit and hlādinī energies of the Lord in the matter of deathlessness, fearlessness and freedom from old age and disease.
In the material world, the planetary systems are arranged in three spheres, called triloka, or Svarga, Martya and Pātāla, and all of them constitute only one fourth of the total sandhinīenergy. Beyond that is the spiritual sky where the Vaikuṇṭha planets exist beyond the coverings of seven material strata. In none of the triloka planetary systems can one experience the status of immortality, full knowledge and full bliss. The upper three planetary systems are called sāttvika planets because they provide facilities for a long duration of life and relative freedom from disease and old age, as well as a sense of fearlessness. The great sages and saints are promoted beyond the heavenly planets to Maharloka, but that also is not the place of complete fearlessness because at the end of one kalpa the Maharloka is annihilated and the inhabitants have to transport themselves to still higher planets. Yet even on these planets no one is immune to death. There may be a comparative extension of life, expansion of knowledge and sense of full bliss, but factual deathlessness, fearlessness and freedom from old age, diseases, etc., are possible only beyond the material spheres of the coverings of the material sky. Such things are situated on the head (adhāyi mūrdhasu).
(Srimad Bhagavatam----2:6:19----purport).

Brahma, with his maya, wanted to test whether Krsna was actually present. These cowherd boys were but expansions of Krsna's personal self (ananda-cinmaya-rasa-pratibhavitabhih (Bs. 5.37)). Later Krsna would show Brahma how He expands Himself into everything as His personal pleasure, ananda-cinmaya-rasa. Hladini saktir asmat: Krsna has a transcendental potency called hladini sakti. He does not enjoy anything that is a product of the material energy. Brahma, therefore, would see Lord Krsna expand His energy.
(Srimad Bhagavatam----10:13:15----purport).

So primarily His three energies are internal, marginal and external. This external energy is also displayed in the three modes of goodness, passion and ignorance. Similarly, the internal potency is also displayed in three spiritual modes—saṁvit, sandhinī and hlādinī. The marginal potency, or the living entities, is also spiritual (prakṛtiṁ viddhi me parām), but the living entities are never equal to the Lord. The Lord is nirasta-sāmya-atiśaya; in other words, no one is greater than or equal to the Supreme Lord. So the living entities, including even such great personalities as Lord Brahmā and Lord Śiva, are all subordinate to the Lord. In the material world also, in His eternal form of Viṣṇu, He maintains and controls all the affairs of the demigods, including Brahmā and Śiva.
(Srimad Bhagavatam----2:6:32----purport).

Kṛṣṇa is always all-spiritual. Aside from the parents of the Personality of Godhead, all the other paraphernalia of His existence are also essentially a manifestation ofsandhinī-śakti, or a transformation of viśuddha-sattva. To make this more clear, it may be said that this sandhinī-śakti of the internal potency maintains and manifests all the variegatedness of the spiritual world. In the kingdom of God, the Lord's servants and maidservants, His consorts, His father and mother and everything else are all transformations of the spiritual existence of sandhinī-śakti. The existential sandhinī-śakti in the external potency similarly expands all the variegatedness of the material cosmos, from which we can have a glimpse of the spiritual field.
(Sri Caitanya Caritamrta----1:4:65----purport).

Śrī Kṛṣṇa cannot enjoy anything that is internally different from Him. Therefore Rādhā and Śrī Kṛṣṇa are identical. The sandhinī portion of Śrī Kṛṣṇa's internal potency has manifested the all-attractive form of Śrī Kṛṣṇa, and the same internal potency, in the hlādinī feature, has presented Śrīmatī Rādhārāṇī, who is the attraction for the all-attractive. No one can match Śrīmatī Rādhārāṇī in the transcendental pastimes of Śrī Kṛṣṇa.
(Sri Caitanya Caritamrta----1:4:71----purport).

The empiric philosophers enjoy a transcendental quality of bliss by philosophical speculation on the Supreme Truth, but beyond that pleasure is the pleasure enjoyed by Brahman in His eternal form of the Personality of Godhead. Brahman bliss is enjoyed by living entities after liberation from material bondage. But Parabrahman, the Personality of Godhead, enjoys eternally a bliss of His own potency, which is called the hlādinī potency. The empiric philosopher who studies Brahman by negation of the external features has not yet learned the quality of the hlādinī potency of Brahman. Out of many potencies of the Omnipotent, there are three features of His internal potency—namely saṁvit, sandhinī and hlādinī. And in spite of their strict adherence to the principles of yama, niyama, āsana, dhyāna, dhāraṇā and prāṇāyāma, the great yogīs and jñānīs are unable to enter into the internal potency of the Lord. This internal potency is, however, easily realized by the devotees of the Lord by dint of devotional service.
(Srimad Bhagavatam----3:1:31----purport).

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. One who does not know how the machine is working may say that it is all iron; nonetheless, in spite of its being iron, the machine has different elements, all working differently to accomplish the purpose for which the machine was made. One wheel runs this way, another wheel runs that way, functioning naturally in such a way that the work of the machine goes on. Consequently we give different names to the different parts of the machine, saying, "This is a wheel," "This is a screw," "This is a spindle," "This is the lubrication," and so on. Similarly, as explained in the Vedas,
parāsya śaktir vividhaiva śrūyate
svābhāvikī jñāna-bala-kriyā ca
(Cc. Madhya 13.65, purport)
Kṛṣṇa's power is variegated, and thus the same śakti, or potency, works in variegated ways. Vividhā means "varieties." There is unity in variety. Thus yogamāyā and mahāmāyā are among the varied individual parts of the same one potency, and all of these individual potencies work in their own varied ways. The saṁvit, sandhinī and āhlādinī potencies—Kṛṣṇa's potency for existence, His potency for knowledge and His potency for pleasure—are distinct from yogamāyā. Each is an individual potency. The āhlādinī potency is Rādhārāṇī. As Svarūpa Dāmodara Gosvāmī has explained, rādhā kṛṣṇa-praṇaya-vikṛtir hlādinī śaktir asmāt (CC.1:1:5). The āhlādinī-śakti is manifested as Rādhārāṇī, but Kṛṣṇa and Rādhārāṇī are the same, although one is potent and the other is potency.
(Srimad Bhagavatam----10:13:57----purport).

This brings up the question of who Śrīmatī Rādhārāṇī is and what Rādhā-Kṛṣṇa is. Actually Rādhā-Kṛṣṇa is the exchange of love—but not ordinary love. Kṛṣṇa has immense potencies, of which three are principal: the internal, the external and the marginal potencies. In the internal potency there are three divisions: samvit, hlādinī and sandhinī. The hlādinī potency is Kṛṣṇa's pleasure potency. All living entities have this pleasure-seeking potency, for all beings are trying to have pleasure. This is the very nature of the living entity. At present we are trying to enjoy our pleasure potency by means of the body in the material condition. By bodily contact we are attempting to derive pleasure from material sense objects. But we should not entertain the nonsensical idea that Kṛṣṇa, who is always spiritual, also tries to seek pleasure on this material plane. In the Bhagavad-gītā Kṛṣṇa describes the material universe as a nonpermanent place full of miseries. Why, then, would He seek pleasure in matter? He is the Supersoul, the supreme spirit, and His pleasure is beyond the material conception.
(Sri Caitanya Caritamrta--introduction).

The activities of the samvit-śakti produce the effect of cognition. Both the Lord and the living entities are cognizant. Śrī Kṛṣṇa, as the Supreme Personality of Godhead, has full knowledge of everything everywhere, and therefore there are no hindrances to His cognition. He can have knowledge merely by glancing over an object, whereas innumerable impediments block the cognition of ordinary living beings. The cognition of the living beings has three divisions: direct knowledge, indirect knowledge and perverted knowledge. Sense perception of material objects by the mundane senses, such as the eye, ear, nose and hand, always produces definitely perverted knowledge. This illusion is a presentation of the material energy, which is influenced by the samvit-śakti in a perverted manner. Negative cognition of an object beyond the reach of sense perception is the way of indirect knowledge, which is not altogether imperfect but which produces only fragmentary knowledge in the form of impersonal spiritual realization and monism. But when the samvit factor of cognition is enlightened by the hlādinī potency of the same internal energy, they work together, and only thus can one attain knowledge of the Personality of Godhead. The samvit-śakti should be maintained in that state. Material knowledge and indirect spiritual knowledge are by-products of the samvit-śakti.
(Sri Caitanya Caritamrta----1:4:67----purport).