"Although the three puruṣas are the shelter of all the universes, Lord Kṛṣṇa is the original source of the puruṣas."
(Sri Caitanya Caritamrta------1:2:105------translation).

"Thus the Personality of Godhead Śrī Kṛṣṇa is the original, primeval Lord, the source of all other expansions. All the revealed scriptures accept Śrī Kṛṣṇa as the Supreme Lord."
(Sri Caitanya Caritamrta------1:2:105------translation).

"The material and the spiritual world are transformations of Kṛṣṇa's external and internal potencies respectively. Therefore Kṛṣṇa is the original source of both the material and the spiritual manifestations."
(Sri Caitanya Caritamrta------2:20:150------translation).

"Kṛṣṇa is the original source of everything and the sum total of everything. He appears as the supreme youth, and His whole body is composed of spiritual bliss. He is the shelter of everything and master of everyone."
(Sri Caitanya Caritamrta------2:20:150------translation).

The Viṣṇu incarnation, although master of the modes of goodness within each universe, is in no way in touch with the influence of material nature. Although Viṣṇu is equal to Kṛṣṇa, Kṛṣṇa is the original source. Viṣṇu is a part, but Kṛṣṇa is the whole. This is the verdict of the Vedic literature. The Brahma-saṁhitā (5.46) gives the example of an original candle which lights a second candle. Although the candles are of equal power, one is still accepted as the original and the other is said to be kindled from the original. The Viṣṇu expansion is like the second candle. He is as powerful as Kṛṣṇa, but the original Viṣṇu is Kṛṣṇa. Brahmā and Lord Śiva are obedient servants of the Supreme Lord, and the Supreme Lord as Viṣṇu is an expansion of Kṛṣṇa.
(Teachings of Lord Caitanya).

Although an incarnation of the material energy, Lord Brahmā is nonetheless the director of the material mode of passion. Similarly, Lord Śiva, although simultaneously one with and different from Lord Kṛṣṇa, is still the incarnation of the mode of darkness. However, Lord Viṣṇu is Kṛṣṇa's personal expansion; therefore He is the director of the mode of goodness and is always transcendentally situated, beyond the jurisdiction of the modes of material nature. Lord Viṣṇu is the original personal expansion of Kṛṣṇa, and Kṛṣṇa is the original source of all incarnations. As far as power is concerned, Lord Viṣṇu is as powerful as Lord Kṛṣṇa because He possesses all the opulences.
(Sri Caitanya Caritamrta------2:20:315------purport).

"Such ecstatic transactions between Kṛṣṇa and the gopīs are possible only in Vṛndāvana, which is full of the opulences of transcendental love. The form of Kṛṣṇa is the original source of all transcendental qualities. It is like a mine of gems. The opulences belonging to all the personal expansions of Kṛṣṇa are to be understood to be bestowed by Kṛṣṇa; therefore Kṛṣṇa is the original source and shelter of everyone."
(Sri Caitanya Caritamrta------2:20:120------translation).

"I (Kṛṣṇa) am the original source of everything. Everything emanates from Me. The wise who perfectly know this engage in My service with love and devotion."
(Sri Caitanya Caritamrta------2:24:189------translation).

Everything is resting on Kṛṣṇa's energy; therefore without Kṛṣṇa's shelter nothing can exist. Kṛṣṇa is the supreme ruler because everything belongs to Him and everything exists on His energy. Kṛṣṇa, being situated in everyone's heart, is the supreme witness. The residences, countries or planets on which we live are also Kṛṣṇa. Kṛṣṇa is the ultimate goal of shelter, and therefore one should take shelter of Kṛṣṇa either for protection or for annihilation of his distress. And whenever we have to take protection, we should know that our protection must be a living force. Kṛṣṇa is the supreme living entity. And since Kṛṣṇa is the source of our generation, or the supreme father, no one can be a better friend than Kṛṣṇa, nor can anyone be a better well-wisher.Kṛṣṇa is the original source of creation and the ultimate rest after annihilation. Kṛṣṇa is therefore the eternal cause of all causes.
(Bhagavad-Gita------9:18------purport).

Kṛṣṇa is the first Nārāyaṇa. In the spiritual world (Vaikuṇṭha) there are unlimited numbers of Nārāyaṇas, who are all the same Personality of Godhead and are considered to be the plenary expansions of the original Personality of Godhead, ŚrīKṛṣṇa. The first form of the Lord Śrī Kṛṣṇa first expands Himself as the form of Baladeva, and Baladeva expands in so many other forms, such as Saṅkarṣaṇa, Pradyumna, Aniruddha, Vāsudeva, Nārāyaṇa, Puruṣa, Rāma and Nṛsiṁha. All these expansions are one and the same viṣṇu-tattva, and Śrī Kṛṣṇa is the original source of all the plenary expansions. He is therefore the direct Personality of Godhead. He is the creator of the material world, and He is the predominating Deity known as Nārāyaṇa in all the Vaikuṇṭha planets. Therefore, His movements amongst human beings is another sort of bewilderment. The Lord therefore says in the Bhagavad-gītā that foolish persons consider Him to be one of the human beings without knowing the intricacies of His movements.
(Srimad Bhagavatam------1:9:18------purport).

As explained in the next verse, Kṛṣṇa is the original source of all living entities. This is confirmed in Bhagavad-gītā (15.7), wherein Kṛṣṇa says:
mamaivāṁśo jīva-loke
jīva-bhūtaḥ sanātanaḥ
manaḥ ṣaṣṭhānīndriyāṇi
prakṛti-sthāni karṣati
"The living entities in this conditioned world are My eternal, fragmental parts. Due to conditioned life, they are struggling very hard with the six senses, which include the mind." All living entities are part and parcel of Kṛṣṇa, and therefore when they revive their original Kṛṣṇa consciousness, they possess all the good qualities of Kṛṣṇa in a small quantity. When one engages himself in the nine processes of devotional service (śravaṇaṁ kīrtanaṁ viṣṇoḥ smaraṇaṁ pāda-sevanam/ arcanaṁ vandanaṁ dāsyaṁ sakhyam ātma-nivedanam (S.B.7:5:23), one's heart becomes purified, and he immediately understands his relationship with Kṛṣṇa.
(Srimad Bhagavatam------5:18:12------purport).

The authorized scriptures have declared that Kṛṣṇa is the original Supreme Lord and the source of all incarnations. In the Bhagavad-gītā (7.7), He says in His own words, mattaḥ parataraṁ nānyat: "O conqueror of wealth, there is no Truth superior to Me." Lord Kṛṣṇa came personally to teach that the highest Absolute Truth is not an impotent material concept. He is the full manifestation of absolute spiritual potencies. Those who cannot grasp this profound truth are fools spinning out endless speculations. That person who, although one, desires to expand and thus becomes many—can such a person be a human being or a formless impersonal entity? When this person decides to expand Himself manyfold, is He doing so in order to destroy Himself? If the Lord were to lose His own identity by expanding Himself into many, that would mean destruction of Himself. Has the Supreme Lord committed such a foolish blunder? Or has the blunder been committed by those who misinterpret the Vedic statements and say that God expanded Himself into many entities and lost His identity? The Supreme Lord can do as He pleases: He can expand Himself as countless incarnations or as multifarious separated energies. And even after expanding Himself in this way, He remains complete and fully Himself, as He is. If this were not so, then how could He be the complete Absolute Whole?
(Renunciation through Wisdom).

Lord Brahmā is described in this verse as the original cause of the cosmic manifestation, and this applies to his position in the material world. There are many, many such controllers, all of whom are created by the Supreme Lord, Viṣṇu. This is illustrated by an incident described in Caitanya-caritāmṛta. When the Brahmā of this particular universe was invited by Kṛṣṇa to Dvārakā, he thought that he was the only Brahmā. Therefore when Kṛṣṇa inquired from His servant which Brahmā was at the door to visit, Lord Brahmā was surprised. He replied that of course Lord Brahmā, the father of the four Kumāras, was waiting at the door. Later, Lord Brahmā asked Kṛṣṇa why He had inquired which Brahmā had come. He was then informed that there are millions of other Brahmās because there are millions of universes. Kṛṣṇa then called all the Brahmās, who immediately came to visit Him. The catur-mukha Brahmā, the four-headed Brahmā of this universe, thought himself a very insignificant creature in the presence of so many Brahmās with so many heads. Thus although there is a Brahmā who is the engineer of each universe, Kṛṣṇa is the original source of all of them.
(Srimad Bhagavatam------7:3:28------purport).

It is also confirmed in the Bhagavad-gītā that the remembrance of the living entity is due to the presence of the Supersoul within the heart. After changing the body, a living creature forgets everything of his past life, but because Nārāyaṇa, the Supersoul, is present within his heart, he is reminded by Him to act according to his past desire. Lord Brahmā wanted to prove that Kṛṣṇa is the original Nārāyaṇa, that He is the source of Nārāyaṇa, and that Nārāyaṇa is not an exhibition of the external energy, māyā, but is an expansion of spiritual energy. The activities of the external energy, or māyā, are exhibited after the creation of this cosmic world, and the original spiritual energy of Nārāyaṇa was acting before the creation. So the expansions of Nārāyaṇa—from Nārāyaṇa to Kāraṇodakaśāyī Viṣṇu, from Kāraṇodakaśāyī Viṣṇu to Garbhodakaśāyī Viṣṇu, from Garbhodakaśāyī Viṣṇu to Kṣīrodakaśāyī Viṣṇu, and from Kṣīrodakaśāyī Viṣṇu to everyone's heart—are actually Kṛṣṇa's expansions, manifestations of His spiritual energy. They are not conducted by the material energy; therefore they are not temporary. Anything conducted by the material energy is temporary, but everything executed by the spiritual energy is eternal.
(Krsna Book).

He then snatched the bundle of chipped rice which was hanging on the shoulder of the poor brāhmaṇa, packed in one corner of his wrapper, and said, "What is this? My dear friend, you have brought Me nice, palatable chipped rice!" He encouraged Sudāmā Vipra, saying, "I consider that this quantity of chipped rice will satisfy not only Me but the whole creation." It is understood from this statement that Kṛṣṇa, being the original source of everything, is the root of the entire creation. As watering the root of a tree immediately distributes water to every part of the tree, so an offering made to Kṛṣṇa, or any action done for Kṛṣṇa, is to be considered the highest welfare work for everyone, because the benefit of such an offering is distributed throughout the creation. Love for Kṛṣṇa is distributed to all living entities.
(Krsna Book).

Your Lordship, being the origin of the life of this material world, is the master and controller of the living entities, both moving and stationary, and you inspire their consciousness. You maintain the mind and the acting and knowledge-acquiring senses, and therefore you are the great controller of all the material elements and their qualities, and you are the controller of all desires.
In this verse it is clearly indicated that the original source of everything is life. Brahmā was instructed by the supreme life, Kṛṣṇa. Kṛṣṇa is the supreme living entity (nityo nityānāṁ cetanaś cetanānām (Kaṭha Upaniṣad 2.2.13)), and Brahmā is also a living entity, but the original source of Brahmā is Kṛṣṇa. Therefore Kṛṣṇa says in Bhagavad-gītā (7.7), mattaḥ parataraṁ nānyat kiñcid asti dhanañjaya: "O Arjuna, there is no truth superior to Me." Kṛṣṇa is the original source of Brahmā, who is the original source of this universe. Brahmā is a representative of Kṛṣṇa, and therefore all the qualities and activities of Kṛṣṇa are also present in Lord Brahmā.
(Srimad Bhagavatam------7:3:29------translation and purport).

Feeling the child to be as heavy as the entire universe and therefore being anxious, thinking that perhaps the child was being attacked by some other ghost or demon, the astonished mother Yaśodā put the child down on the ground and began to think of Nārāyaṇa. Foreseeing disturbances, she called for the brāhmaṇas to counteract this heaviness, and then she engaged in her other household affairs. She had no alternative than to remember the lotus feet of Nārāyaṇa, for she could not understand that Kṛṣṇa was the original source of everything.
(Srimad Bhagavatam------10:7:19------translation).