Isvara and Sakti

Chapter 1 Slokas 12-15
The Principal Evolver, who is both perceptible and imperceptible, is Vāsudeva. TheImperceptible part of the Lord is endowed with dual powers, while the Perceptible with triplepowers. The three powers are Śrī-Śakti (Mother Lakshmi) with Sattva-Guṇa, Bhū-Śakti (MotherEarth) with Rajo-Guṇa and Nīla-Śakti with Tamo-Guṇa. Apart from the three, the fourth kind ofViṣṇu, influenced by Śrī-Śakti and Bhū-Śakti, assumes the form of Saṅkarṣaṇa with Tamo-Guṇa, ofPradyumna with Rajo-Guṇa and of Aniruddha with Sattva-Guṇa

Sarva-avatārī kṛṣṇa svayaṁ bhagavān tāṅhāra dvitīya deha śrī-balarāma eka-i svarūpa doṅhe, bhinna-mātra kāya ādya kāya-vyūha, kṛṣṇa-līlāra sahāya
“
The Supreme Personality of Godhead, Kṛṣṇa, is the fountainhead of all incarnations. LordBalarāma is His second body. They are both one and the same identity. They differ only inform. He is the first bodily expansion of Kṛṣṇa, and He assists in Lord Kṛṣṇa's transcendentalpastimes.”
Caitanya-caritamrta, Adi-lila
5.5

sei para-vyome nārāyaṇera cāri pāśe dvārakā-catur-vyūhera dvitīya prakāśe vāsudeva-saṅkarṣaṇa-pradyumnāniruddha 'dvitīya catur-vyūha' ei--turīya, viśuddha
“
In that spiritual sky, on the four sides of Nārāyaṇa, are the second expansions of thequadruple expansions of Dvārakā. Vāsudeva, Saṅkarṣaṇa, Pradyumna and Aniruddhaconstitute this second quadruple. They are purely transcendental.”

Srila Prabhupada explains:“The supreme living entity, Kṛṣṇa, eternally manifests Himself as the
catur-vyūha
, or quadrupleplenary expansion. The purport of this prayer is that one should give up his false ego and pray to this
catur-vyūha
by offering Them obeisances. Although the Absolute Truth is one without a second, theAbsolute Truth displays His unlimited opulences and potencies by expanding Himself in innumerableplenary forms, of which the
catur-vyūha
is a principal expansion. The original being is Vāsudeva, the Personality of Godhead. When the Godhead manifests His primeval energies and opulences, He is called Saṅkarṣaṇa. Pradyumna is the basis of the Viṣṇu expansion who is the soul of the entire universe, and Aniruddha is the basis of the personal manifestation of Viṣṇu as the Super soul of every individual entity within the universe. Among the four plenary expansions mentioned here, the original expansion is Vāsudeva, and the other three are considered to be particular manifestations of Him.”[Srimad-Bhagavatam11.5.29-30, Purport]
“The expansions of different forms of the Lord, as from Kṛṣṇa to Baladeva to Saṅkarṣaṇa, fromSaṅkarṣaṇa to Vāsudeva, from Vāsudeva to Aniruddha, from Aniruddha to Pradyumna and thenagain to second Saṅkarṣaṇa and from Him to the Nārāyaṇa
puruṣāvatāras , and innumerable otherforms, which are compared to the constant flowing of the uncountable waves of a river, are all oneand 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 [Sri Isopanisad , Invocation]. [Srimad-Bhagavatam 2.4.10 Purport]
mahā-lakṣmīr deveśasya bhinnābhinna-rūpā cetanācetanātmikā sā devī tri-vidhā bhavati śakty-ātmanā icchā-śaktiḥ kriyā-śaktiḥ sākṣāc-chaktir iti icchā-śaktis tri-vidhā bhavati, śrī-bhūmi-nīlātmikā
"Mahā-Lakṣmī, the supreme energy of the Lord, is experienced in different ways. She isdivided into material and spiritual potencies, and in both features she acts as the willingenergy, creative energy and the internal energy. The willing energy is again divided into three,namelyśrī, bhū and nīlā ."[Sītopaniṣad]
Śrīla Jīva Gosvāmī Prabhu states:"The Padma Purāṇa refers to the eternally auspicious abode of Godhead, which is full in allopulences, including the energies
śrī, bhū and nīlā . The Mahā-saṁhitā , which discusses thetranscendental name and form of Godhead, also mentions Durgā as the potency of the Supersoul inrelationship with the living entities. The internal potency acts in relation with His personal affairs, andthe material potency manifests the three modes."