Vaisesika Sūtra 7.1.23

तदभावादणुमनः ॥२३॥

tad-abhāvād aṇu-manaḥ ॥23॥

[तद्-अभावात् (tad-abhāvāt) - from the absence of that; अणु-मनः (aṇu-manaḥ) - the mind becomes minute;]

When that (cause) is absent, the mind becomes subtle or minute.