Vaisesika Sūtra 8.1.02

तत्रात्मा मनश्चाप्रत्यक्षे ॥२॥

tatrātmā manaścāpratyakṣe ॥2॥

[तत्र (tatra) - there; आत्मा (ātmā) - Ātmā; मनः (manaḥ) - mind; च (ca) - and; अप्रत्यक्षे (apratyakṣe) - not manifest;]

There, the Ātmā and the mind are not directly perceivable.