Bhashya
आदित्यो ब्रह्मेत्यादेश उपदेश, तस्योपव्याख्यानं क्रियतेस्तुत्यर्थम् ।असत् अव्याकृतनामरूपम् इदं जगत् अशेषमग्रेप्रागवस्थायामुत्पत्ते आसीत् न त्वसदेव, 'कथमसतः सञ्जा-येत' इति असत्कार्यत्वस्य प्रतिषेधात् ।ननु इहासदेवेतिविधानाद्विकल्प स्यात् ।न, क्रियास्विब वस्तुनि विकल्पानु-पपत्ते ।कथ तर्हि इदमसदेवेति ? नन्ववोचाम अव्याकृतनामरूपत्वादसदिवासदिति ।नन्वेवशब्दोऽवधारणार्थ , सत्यमे-वम्, न तु सत्त्वाभावमवधारयति, कि तर्हि, व्याकृतनामअथ यत्तदजायत गर्भरूप तस्मिन्नण्डे, सोऽसावादित्य , तमादित्य जायमान घोषा शब्दा उलूळव उरूरवो विस्ती- र्णरवा उदतिष्ठन् उत्थितवन्त ईश्वरस्येवेह प्रथमपुत्रजन्मनि सर्वाणि च स्थावरजङ्गमानि भूतानि सर्वे च तेषा भूताना कामा काम्यन्त इति विषया स्त्रीवस्त्रान्नादय ।यस्मादा- दित्यजन्मनिमित्ता भूतकामोत्पत्ति , तस्मादद्यत्वेऽपि तस्या दित्यस्यादय प्रति प्रत्यायन प्रति अस्तगमन च प्रति, अथवा पुन पुन प्रत्यागमन प्रत्यायन तत्प्रति तन्निमित्तीकृत्येत्यर्थ , सर्वाणि च भूतानि सर्वे च कामा घोषा उलूळवश्चानुति- ष्ठन्ति ।प्रसिद्ध हि एतदुदयादौ सवितु ॥
In plain words
The statement that the sun is Brahman is explained further here by way of praise. Before manifestation, this entire universe of name and form existed in a subtle, unmanifest state—not as absolute nothingness, for scripture forbids the view that something can arise from nothing. If the text says it was 'non-existent,' this is simply because name and form were unexpressed, like something hidden. The restrictive word 'eva' here does not mean total non-existence, but merely points to that unmanifest condition. When the newborn sun emerged as an embryo from within that cosmic egg, joyous shouts, roars, and great celebrations arose, just as they do when a lord's firstborn son comes into the world. All creatures and all their desires—for women, clothing, food, and every enjoyment—awoke. Because the birth of desires follows the birth of the sun, even today at every sunrise, approach, and setting of the sun, all beings and all desires re-enact those celebratory sounds. This is a well-known truth at the rising of the sun.
Close to the Sanskrit
The sun is Brahman—this teaching, its further explanation is made for the sake of praise. The unmanifest name-and-form universe existed entirely in the prior state before origination, not indeed as absolute non-existence, due to the prohibition of the non-existent effect doctrine. Now, if here the text prescribes it as non-existent, might there be an option? No, since options are inadmissible in matters of fact as opposed to ritual actions. How then is this 'non-existent indeed'? We stated: because of unmanifest name-and-form, it is spoken of as non-existent-like. Now, the word 'eva' is for restriction; that is true, it does not restrict the absence of existence, but rather restricts the unmanifest name-form. And whatever was born as an embryonic form in that egg, that very sun—at that sun's birth, sounds, ululations, vast roars, and widespread noises arose. Just like at the birth of a first son of a lord in this world, all movable and immovable beings and all desires of those beings—such as women, garments, food, and other objects—are desired. Because the origin of beings' desires is caused by the sun's birth, therefore even today, regarding the sun's rising, approach, and setting, or rather its repeated return and approach, treating that as the cause, all beings, all desires, sounds, and ululations accompany it. For this is well known at the sunrise and other times of the sun.