Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 2
Sanskrit:
सत एव पदार्थस्य स्वरूपावस्थितस्य यत् ।कैवल्यं परममहानविशेषो निरन्तर: ॥ २ ॥
ITRANS:
sata eva padārthasyasvarūpāvasthitasya yatkaivalyaṁ parama-mahānaviśeṣo nirantaraḥ
Translation:
Atoms are the ultimate state of the manifest universe. When they stay in their own forms without forming different bodies, they are called the unlimited oneness. There are certainly different bodies in physical forms, but the atoms themselves form the complete manifestation.