The words sarva-vastuni vastu-svarūpaḥ indicate that the Supreme Lord is the active principle of everything. As described in the Brahma-saṁhitā (5.35) :

eko ’py asau racayituṁ jagad-aṇḍa-koṭiṁ yac-chaktir asti jagad-aṇḍa-cayā yad-antaḥ aṇḍāntara-stha-paramāṇu-cayāntara-sthaṁ govindam ādi-puruṣaṁ tam ahaṁ bhajāmi

“I worship the Personality of Godhead, Govinda, who enters the existence of every universe and every atom by one of His plenary portions and thus manifests His infinite energy throughout the material creation.” By His one plenary portion as Paramātmā, antaryāmī, the Lord is all-pervading throughout the unlimited universes. He is the pratyak, or antaryāmī, of all living entities. The Lord says in Bhagavad-gītā (13.3) , kṣetra-jṣaṁ cāpi māṁ viddhi sarva-kṣetreṣu bhārata: “O scion of Bharata, you should understand that I am also the knower in all bodies.” Because the Lord is the Supersoul, He is the active principle of every living entity and even the atom ( aṇḍāntara-stha-paramāṇu-cayāntara-stham ). He is the actual reality. According to various stages of intelligence, one realizes the presence of the Supreme in everything through the manifestations of His energy. The entire world is permeated by the three guṇas, and one can understand His presence according to one’s modes of material nature.