Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 1
मैत्रेय उवाचचरम: सद्विशेषाणामनेकोऽसंयुत: सदा ।परमाणु: स विज्ञेयो नृणामैक्यभ्रमो यत: ॥ १ ॥
maitreya uvācacaramaḥ sad-viśeṣāṇāmaneko ’saṁyutaḥ sadāparamāṇuḥ sa vijñeyonṛṇām aikya-bhramo yataḥ
The material manifestation’s ultimate particle, which is indivisible and not formed into a body, is called the atom. It exists always as an invisible identity, even after the dissolution of all forms. The material body is but a combination of such atoms, but it is misunderstood by the common man.
The atomic description of the Śrīmad-Bhāgavatam is almost the same as the modern science of atomism, and this is further described in the Paramāṇu-vāda of Kaṇāda. In modern science also, the atom is accepted as the ultimate indivisible particle of which the universe is composed. Śrīmad-Bhāgavatam is the full text of all descriptions of knowledge, including the theory of atomism. The atom is the minute subtle form of eternal time.