He exists everywhere and He is everything .Whatever we see and hear that is Narayana only because He exists inside and outside of everything whichever exists in this world-'yacca kimcit jagat sarvam drishyate shrooyatepi va antarbahisca tat sarvam vyapya narayana sthitah". Actually He only exists nothing else. He is the inner cause and power by which things exist.
Visvam - He whose manifestation is the whole universe of forms: the Viraat-Purusha. The cause is always present in the effects and as such That Form from which the whole universe has emerged out can only be its own manifestation.The whole cosmos of gross forms is His own expression, and therefore, He is called as Viraatpurusha. ‘Sa eva Sarva- Bhootaatmaa Visvaroopo Yato-Avyayah’. The Sanskrit term Visvam comes from the root Vis, to enter: Thus it means He who has created and entered into the entire universe, as the All-Pervading Reality. It can also mean, That into which the entire universe has entered to remain therein established. In the Upanishads also we have assertions of similar ideas. It is only when intellectually, we view the Lord that we come to recognise Him as the ‘cause’ for the universe. When viewed through contemplation, since the effect is nothing other than the cause, there can be no world other than Him. In fact, there is nothing other than the Supreme. In the Mandukya Upanishad we read ‘Omkaara Evedam Sarvam’. In Geeta ‘OM ltyekaaksharam Brahma’.
Vishnuh -The term Vishnu is dissolved as Veveshti Vyaapnoti iti Vishnuh-That which pervades everywhere is Vishnu. That which has the nature of pervasiveness is Vishnu. He is the one who pervades all and nothing ever in pervades Him. ‘Eesaavaasyam Idam Sarvam’-All this is indwelt, pervaded by the Lord. This very same idea is described the typical style of the Puranas, in the incarnation of the Lord as Vaamana, the short-boy (Vamana), who, with His three feet, measured the entire universe. Because of this act, the Lord got the name Vishnu, says Mahaabhaarata. Vishnu Purana (3-1) says: The root Vis means ‘to enter’. The entire world of things and beings is pervaded by Him and the Upanishad emphatically insists in its mantra ‘whatever that is there is the world of change’. Hence it means that He is not limited by space (Desa), time (Kaala) or substance (Vastu).