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-mentioned sandhinī, saṁvit and hlādinī energies of the Lord in the matter of deathlessness, fearlessness and freedom from old age and disease.
(Srimad Bhagavatam------2:6:19------purport).

The Lord is described here as omnipotent by three energies (tri-śakti-dhṛk). 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.
(Srimad Bhagavatam------2:6:32------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 absolute Personality of Godhead, Śrī Kṛṣṇa, is the omnipotent form of transcendental existence, knowledge and bliss in full. His internal potency is exhibited first as sat, or existence—or, in other words, as the portion that expands the existence function of the Lord. When the same potency displays full knowledge it is called cit, or samvit, which expands the transcendental forms of the Lord. Finally, when the same potency plays as a pleasure-giving medium it is known as hlādinī, or the transcendental blissful potency. Thus the Lord manifests His internal potency in three transcendental divisions.
(Sri Caitanya Caritamrta-------1:4:56------purport).

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, sandhinī and 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).

When not manifested, the modes of material nature are said to be in goodness. When they are externally manifested and active in producing the varieties of material existence, they are said to be in passion. And when there is a lack of activity and variegatedness, they are said to be in ignorance. In other words, the pensive mood is goodness, activity is passion, and inactivity is ignorance. Above all these mundane qualitative manifestations is viśuddha-sattva. When it is predominated by the sandhinī potency, it is perceivable as the existence of all that be. When predominated by the samvit potency, it is perceived as knowledge in transcendence. And when predominated by the hlādinī potency, it is perceived as the most confidential love of Godhead. Viśuddha-sattva, the simultaneous manifestation of these three in one, is the main feature of the kingdom of God.
(Sri Caitanya Caritamrta-------1:4:62------purport).

Each of the three divisions of the internal potency—the sandhinī, samvit and hlādinī energies—influences one of the external potencies by which the conditioned souls are conducted. Such influence manifests the three qualitative modes of material nature, proving definitely that the living entities, the marginal potency, are eternally servitors of the Lord and are therefore controlled by either the internal or the external potency.
(Sri Caitanya Caritamrta-------1:4:62------purport).

Hlādinī is His aspect of bliss; sandhinī, of eternal existence; and samvit, of cognizance, which is also accepted as knowledge.
In his thesis Bhagavat-sandarbha (103), Śrīla Jīva Gosvāmī explains the potencies of the Lord as follows: The transcendental potency of the Supreme Personality of Godhead by which He maintains His existence is called sandhinī. The transcendental potency by which He knows Himself and causes others to know Him is called samvit. The transcendental potency by which He possesses transcendental bliss and causes His devotees to have bliss is called hlādinī.
The total exhibition of these potencies is called viśuddha-sattva, and this platform of spiritual variegatedness is displayed even in the material world when the Lord appears here.
(Sri Caitanya Caritamrta-------1:4:62------purport).