Vaisesika Sūtra 4.1.07

सत्यपि द्रव्यत्वे महत्त्वे रूपसंस्काराभावाद् वायोरनुपलब्धिः ॥७॥

Though air is a substance formed from mahat, the primordial substance, it is not perceived due to absence of a well-formed form.