सनात् इति निपातः चिरार्थवचनः ।कालश्च परस्यैव विकल्पना कापि ।' परस्य ब्रह्मणो रूपं पुरुष: प्रथमं द्विज ।व्यक्ताव्यक्ते तथैवान्ये रूपे कालस्तथापरम्' इति विष्णुपुराणे ।सर्वकारणत्वात् विरिश्चयादीनामपि सनातनानामतिशयेन सनातनत्वात् सनातनतमः ।बडबानलस्य कपिलो वर्ण इति तद्रूपी कपिलः ।कं जलं रश्मिभिः पिवन कपिः सूर्यः; कपिः वराहो वा, 'कपिराहः श्रे ष्टच' इति वचनात् ।प्रलये अस्मिन्नपियन्ति जगन्तीति
In plain words
Sanat is an ancient term denoting everlasting duration. Time itself is a particular manifestation of the Supreme. As the Vishnu Purana states: 'The primary form of supreme Brahman is the Purusha, O twice-born; the manifest and unmanifest are two other aspects, and time is yet another.' Because He is the ultimate cause of all and supremely eternal even compared to ancient deities like Brahmā, He is Sanātanatama, the most ancient. He assumes the form of Kapila, matching the hue of the submarine fire. He is Kapi, the sun drawing up water with its rays, or the divine Boar, according to the teaching that Kapi is preeminent. Into Him all worlds merge during the cosmic dissolution.
Close to the Sanskrit
Sanat is an indeclinable word expressing antiquity. And time is some specific formulation of the supreme alone. 'The form of the supreme Brahman is the person first, O twice-born; the manifest and unmanifest are two other forms, and time is another' is in the Vishnu Purana. Because of being the cause of all and because of being supremely eternal even among eternal ones like Virinchi, He is Sanatanatama. Kapila is of that form, being of the color of submarine fire. Kapi is the sun drinking water with rays; or Kapi is the boar, because of the statement 'Kapi is said to be the best'. In this dissolution the worlds merge into Him, thus.