ksetrajña atma purusah puranah
saksat svayam jyotir ajah paresah
narayano bhagavan vasudevah
atma-svarupena nivista iset
evam paro bhagavan vasudevah
ksetrajña atmedam anupravistah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
There are two kinds of ksetrajña — the living entity, as explained above, and the Supreme Personality of Godhead, who is explained as follows. He is the all-pervading cause of creation. He is full in Himself and is not dependent on others. He is perceived by hearing and direct perception. He is self-effulgent and does not experience birth, death, old age or disease. He is the controller of all the demigods, beginning with Lord Brahma. He is called Narayana, and He is the shelter of living entities after the annihilation of this material world. He is full of all opulences, and He is the resting place of everything material. He is therefore known as Vasudeva, the Supreme Personality of Godhead. By His own potency, He is present within the hearts of all living entities, just as the air or vital force is within the bodies of all beings, moving and nonmoving. In this way He controls the body. In His partial feature, the Supreme Personality of Godhead enters all bodies and controls them.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This is confirmed in Bhagavad-gita (15.15). Sarvasya caham hrdi sannivisto mattah smrtir jñanam apohanam ca. Every living being is controlled by the supreme living being, Paramatma, who resides within everyone’s heart. He is the purusa, the purusa-avatara, who creates this material world. The first purusa-avatara is Maha-Visnu, and that Maha-Visnu is the plenary portion of the plenary portion of the Supreme Personality of Godhead, Krsna. Krsna’s first expansion is Baladeva, and His next expansions are Vasudeva, Sankarsana, Aniruddha and Pradyumna. Vasudeva is the original cause of the brahmajyoti, and the brahmajyoti is the expansion of the rays of the body of Vasudeva.
yasya prabha prabhavato jagad-anda-koti-
tad brahma niskalam anantam asesa-bhutam
govindam adi-purusam tam aham bhajami
“I worship Govinda, the primeval Lord, who is endowed with great power. The glowing effulgence of His transcendental form is the impersonal Brahman, which is absolute, complete and unlimited and which displays the varieties of countless planets, with their different opulences, in millions and millions of universes.” (Brahma-samhita 5.40) The Supreme Personality of Godhead is thus described in Bhagavad-gita:
maya tatam idam sarvam
na caham tesv avasthitah
“By Me, in My unmanifested form, this entire universe is pervaded. All beings are in Me, but I am not in them.” (Bg. 9.4)
This is the position of the plenary expansions of Krsna as the all-pervading Vasudeva, Sankarsana, Pradyumna and Aniruddha.