Yoga Sutras of Patanjali · 4.19

न तत्स्वाभासं दृश्यत्वात्॥१९॥

na tat svābhāsaṁ dṛśyatvāt

The mind is not self-illuminating, because it is itself an object of perception.

— Yoga Sutras of Patanjali 4.19

Source: Sanskrit attributed to Patanjali (c. 2nd century BCE – 4th century CE). Public-domain English readings drawn from Swami Vivekananda's 'Raja Yoga' (1896) and Charles Johnston's 'The Yoga Sutras of Patanjali' (1912).