Vaisesika Sūtra 9.1.06

असदिति भूतप्रत्यक्षाभावात् भूतस्मृतेर्विरोधिप्रत्यक्षवत् ॥६॥

asat iti bhūta-pratyakṣa-abhāvāt bhūta-smṛteḥ virodhi-pratyakṣa-vat ॥6॥

[असत् (asat) - non-existent; इति (iti) - thus; भूत (bhūta) - of a past entity; प्रत्यक्ष (pratyakṣa) - perception; अभावात् (abhāvāt) - due to absence; भूतस्मृतेः (bhūta-smṛteḥ) - of memory of the past entity; विरोधि (virodhi) - opposed; प्रत्यक्षवत् (pratyakṣavat) - like perception;]

Non-existence is due to the absence of perception of a past entity and due to opposition of the present perception with the memory of that entity.