SB 5.20.5
pratnasya visno rupam yat
satyasyartasya brahmanah
amrtasya ca mrtyos ca
suryam atmanam imahiti
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
[This is the mantra by which the inhabitants of Plaksadvipa worship the Supreme Lord.] Let us take shelter of the sun-god, who is a reflection of Lord Visnu, the all-expanding Supreme Personality of Godhead, the oldest of all persons. Visnu is the only worshipable Lord. He is the Vedas, He is religion, and He is the origin of all auspicious and inauspicious results.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Visnu is even the Supreme Lord of death, as confirmed in Bhagavad-gita (mrtyuh sarva-haras caham). There are two kinds of activity — auspicious and inauspicious — and both are controlled by Lord Visnu. Inauspicious activities are said to be behind Lord Visnu, whereas auspicious activities stand before Him. The auspicious and the inauspicious exist throughout the entire world, and Lord Visnu is the controller of them both.
In regard to this verse, Srila Madhvacarya says:
surya-somagni-varisa-
vidhatrsu yatha-kramam
plaksadi-dvipa-samsthasu
sthitam harim upasate
There are many lands, fields, mountains and oceans throughout the creation, and everywhere the Supreme Personality of Godhead is worshiped by His different names.
Srila Viraraghava Acarya explains this verse of Srimad-Bhagavatam as follows. The original cause of the cosmic manifestation must be the oldest person and must therefore be beyond material transformations. He is the enjoyer of all auspicious activities and is the cause of conditional life and also liberation. The demigod Surya, who is categorized as a very powerful jiva, or living entity, is a representation of one of the parts of His body. We are naturally subordinate to powerful living entities, and therefore we can worship the various demigods as living beings who are powerful representatives of the Supreme Personality of Godhead. Although the worship of the sun-god is recommended in this mantra, He is worshiped not as the Supreme Personality of Godhead but as His powerful representative.
In the Katha Upanisad (1.3.1) it is said:
rtam pibantau sukrtasya loke
guham pravistau parame parardhe
chayatapau brahmavido vadanti
pañcagnayo ye ca tri-naciketah
“O Naciketa, the expansions of Lord Visnu as the tiny living entity and the Supersoul are both situated within the cave of the heart of this body. Having entered that cavity, the living entity, resting on the chief of the life airs, enjoys the results of activities, and the Supersoul, acting as witness enables him to enjoy them. Those who are well-versed in knowledge of Brahman and those householders who carefully follow the Vedic regulations say that the difference between the two is like the difference between a shadow and the sun.”
In the Svetasvatara Upanisad (6.16) it is said:
sa visvakrd visvavidatmayonih
jñah kalakaro guni sarvavid yah
pradhana-ksetrajña-patir gunesah
samsara-moksa-sthiti-bandha-hetuh
“The Supreme Lord, the creator of this cosmic manifestation, knows every nook and corner of His creation. Although He is the cause of creation, there is no cause for His appearance. He is fully aware of everything. He is the Supersoul, the master of all transcendental qualities, and He is the master of this cosmic manifestation in regard to bondage to the conditional state of material existence and liberation from that bondage.”
Similarly, in the Taittiriya Upanisad (2.8) it is said:
bhisasmad vatah pavate
bhisodeti suryah
bhisasmad agnis candras ca
mrtyur dhavati pañcamah
“It is out of fear of the Supreme Brahman that the wind is blowing, out of fear of Him that the sun regularly rises and sets, and out of fear of Him that fire acts. It is only due to fear of Him that death and Indra, the King of heaven, perform their respective duties.”
As described in this chapter, the inhabitants of the five islands beginning with Plaksadvipa worship the sun-god, the moon-god, the fire-god, the air-god and Lord Brahma respectively. Although they engage in the worship of these five demigods, however, they actually worship Lord Visnu, the Supersoul of all living entities, as indicated in this verse by the words pratnasya visno rupam. Visnu is brahma, amrta, mrtyu — the Supreme Brahman and the origin of everything, auspicious and inauspicious. He is situated in the heart of everyone, including all the demigods. As stated in Bhagavad-gita (7.20), kamais tais tair hrta-jñanah prapadyante ’nya devatah: those whose minds are distorted by material desires surrender unto the demigods. People who are almost blind because of lusty desires are recommended to worship the demigods to have their material desires fulfilled, but actually those desires are not fulfilled by the material demigods. Whatever the demigods do is done with the sanction of Lord Visnu. People who are too lusty worship various demigods instead of worshiping Lord Visnu, the Supersoul of all living entities, but ultimately it is Lord Visnu they worship because He is the Supersoul of all demigods.