Yoga Sutras of Patanjali · 2.6

दृग्दर्शनशक्त्योरेकात्मतेवास्मिता ॥६॥

dṛg-darśana-śaktyor ekātmatā iva asmitā

Egoism is the appearance of one and the same identity in the seer and in the instrument of seeing.

— Yoga Sutras of Patanjali 2.6

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).