The external potency of Godhead, called māyā, can never associate with the Lord, just as darkness cannot remain in the presence of light; yet darkness, being but an illusory and temporary covering of light, has no existence independent of light.
(Sri Caitanya Caritamrta------1:1:34------purport).

When Śrī Caitanya Mahāprabhu danced, He forgot Himself and was simply absorbed in ecstatic bliss. But His internal potency arranged everything perfectly. This is the difference between the internal and external potency. In the material world, the external potency (material energy) can act only after one endeavors at great length, but when the Supreme Lord desires, everything is performed automatically by the internal potency. By His will, things happen so nicely and perfectly that they appear to be carried out automatically. Sometimes the activities of the internal potency are exhibited in the material world.
(Sri Caitanya Caritamrta------2:13:65------purport).

The almighty Personality of Godhead has three potencies—internal, external and marginal. The conditioned souls, who are condemned due to their forgetfulness of the Lord, are put under the control of the external potency when she creates the material world. The three modes of material nature keep the living entity in a constant state of fear (bhayaṁ dvitīyābhiniveśataḥ). The conditioned soul is always fearful due to being controlled by the external potency; therefore the conditioned soul should always pray to the almighty Lord to conquer the external potency (māyā) so that she will no longer manifest her powers, which bind all living entities, moving and inert. By praying in this way one will become eligible to remain constantly in the association of the Lord, thus fulfilling the mission of going back home, back to Godhead.
(Sri Caitanya Caritamrta------2:15:180------purport).

The Lord has many potencies, and He is nondifferent from all these potencies. Because the potencies and the potent cannot be separated, they are identical. Kṛṣṇa is described as the source of all potencies, and He is also identified with the external potency, the material energy. Kṛṣṇa also has internal potencies, or spiritual potencies, which are always engaged in His personal service. His internal potency is different from His external potency. Kṛṣṇa's internal potency and Kṛṣṇa Himself, who is the potent, are always identical.
(Sri Caitanya Caritamrta------2:22:7------purport).

When the living being desires to be an enjoyer of material energy (illusory phenomena), the Lord covers the living being in the mystery of forgetfulness, and thus the living being misinterprets the gross body and subtle mind to be his own self. And by culture of transcendental knowledge, when the living being prays to the Lord for deliverance from the clutches of forgetfulness, the Lord, by His causeless mercy, removes the living being's illusory curtain, and thus he realizes his own self. He then engages himself in the service of the Lord in his eternal constitutional position, becoming liberated from the conditioned life. All this is executed by the Lord either through His external potency or directly by the internal potency.
(Srimad Bhagavatam------1:3:33------purport).

A common living being cannot extend its influence over another common living being by its all-pervasiveness, but the Supreme Supersoul, the Personality of Godhead, is unlimitedly able to exert His influence over all places and all times and over all living beings. And because He is all-pervasive, unlimited by time and space, He can appear even within the womb of the mother of child Parīkṣit. He is mentioned herein as the protector of the righteous. Anyone who is a surrendered soul unto the Supreme is righteous, and he is specifically protected by the Lord in all circumstances. The Lord is the indirect protector of the unrighteous also, for He rectifies their sins through His external potency.
(Srimad Bhagavatam------1:12:11------purport).

Because they are between the internal and external potencies, the eternally transcendental living entities are called the marginal potency of the Lord. Factually, the living entities are not meant to be so conditioned by material energy, but due to their being affected by the false sense of lording it over the material energy, they come under the influence of such potency and thus become conditioned by the three modes of material nature. This external energy of the Lord covers up the pure knowledge of the living entities eternally existing with Him, but the covering is so constant that it appears that the conditioned soul is eternally ignorant. Such is the wonderful action of māyā, or external energy manifested as if materially produced. By the covering power of the material energy, the material scientist cannot look beyond the material causes, but factually, behind the material manifestations, there are adhibhūta, adhyātma and adhidaiva actions, which the conditioned soul in the mode of ignorance cannot see. The adhibhūta manifestation entails repetitions of births and deaths with old age and diseases, the adhyātma manifestation conditions the spirit soul, and the adhidaiva manifestation is the controlling system. These are the material manifestations of cause and effect and the sense of responsibility of the conditioned actors.
(Srimad Bhagavatam------2:5:19------purport).

The glories of the Lord, in the transcendental seventy-five percent of the Lord's internal potency, are stated in the Padma Purāṇa (Uttara-khaṇḍa). It is said there that those planets in the spiritual sky, which comprises the seventy-five percent expansion of the internal potency of the Lord, are far, far greater than those planets in the total universes composed of the external potency of the Lord. In the Caitanya-caritāmṛta, the total universes in the external potency of the Lord are compared to a bucketful of mustard seeds. One mustard seed is calculated to be a universe itself. In one of the universes, in which we are now living, the number of planets cannot be counted by human energy, and so how can we think of the sum total in all the universes, which are compared to a bucketful of mustard seeds? And the planets in the spiritual sky are at least three times the number of those in the material sky. Such planets, being spiritual, are in fact transcendental to the material modes; therefore they are constituted in the mode of unalloyed goodness only. The conception of spiritual bliss (brahmānanda) is fully present in those planets. Each of them is eternal, indestructible and free from all kinds of inebrieties experienced in the material world.
(Srimad Bhagavatam------2:6:18------purport).

Since we generally have the experience of the temporary, material world and conditioned souls trying to lord it over the material worlds, Brahmājī explained to Nāradadeva that this temporary world is the work of the external potency of the Lord and that the conditioned souls struggling here for existence are the marginal potency of the Supreme Lord, the Personality of Godhead. There is no cause for all these phenomenal activities but Him, Hari, the Supreme Lord, who is the primeval cause of all causes. This does not mean, however, that the Lord Himself is distributed impersonally. He is aloof from all these interactions of the external and marginal potencies. In the Bhagavad-gītā (9.4) it is confirmed that by His potencies alone He is present everywhere and anywhere. Everything that is manifested rests on His potency only, but He, as the Supreme Personality of Godhead, is always aloof from everything. The potency and the potent are simultaneously one and different from one another.
(Srimad Bhagavatam------2:7:50------purport).

The consciousness of the living being is always present and never changes under any circumstances, as above mentioned. When a living man moves from one place to another, he is conscious that he has changed his position. He is always present in the past, present and future, like electricity. One can remember incidents from his past and can conjecture about his future also on the basis of past experience. He never forgets his personal identity, even though he is placed in awkward circumstances. How then can the living entity become forgetful of his real identity as pure spirit soul and identify with matter unless influenced by something beyond himself? The conclusion is that the living entity is influenced by the avidyā potency, as confirmed in both the Viṣṇu Purāṇa and the beginning of Śrīmad-Bhāgavatam. The living entity is mentioned in Bhagavad-gītā (7.5) as parā prakṛti, and in the Viṣṇu Purāṇa he is mentioned as the parā śakti. He is part and parcel of the Supreme Lord as potency and not as the potent. The potent can exhibit many potencies, but the potency cannot equal the potent at any stage. One potency may be overcome by another potency, but to the potent, all potencies are under control. The jīva potency, or the kṣetrajña-śakti of the Lord, has the tendency to be overpowered by the external potency, avidyā-karma-saṁjñā, and in this way he is placed in the awkward circumstances of material existence. The living entity cannot be forgetful of his real identity unless influenced by the avidyā potency. Because the living entity is prone to the influence of the avidyā potency, he can never equal the supreme potent.
(Srimad Bhagavatam------3:7:5------purport).

By the cooperation of material nature, which is considered to be prakṛti, and the Supreme Personality of Godhead, who is considered the puruṣa, all the affairs of the universe are going on nicely in their proper order. prakṛti, material nature, is also described in the Brahma-saṁhitā (5.44) as follows:
sṛṣṭi-sthiti-pralaya-sādhana-śaktir ekā
chāyeva yasya bhuvanāni bibharti durgā
icchānurūpam api yasya ca ceṣṭate sā
govindam ādi-puruṣaṁ tam ahaṁ bhajāmi
"The external potency, māyā, who is of the nature of the shadow of the cit (spiritual) potency, is worshiped by all people as Durgā, the creating, preserving and destroying agency of this mundane world. I adore the primeval Lord Govinda, in accordance with whose will Durgā conducts herself." Material nature, the external energy of the Supreme Lord, is also known as Durgā, or the female energy that protects the great fort of this universe. The word Durgā also means fort. This universe is just like a great fort in which all the conditioned souls are kept, and they cannot leave it unless they are liberated by the mercy of the Supreme Personality of Godhead.
(Srimad Bhagavatam------5:23:3------purport).