Jñānāgni

Narendra — All is one, isn’t it?

Sri Ramakrishna — No, beyond one and two.

(source)

When the mind perceives duality then there is both duality and its counterpart, which is unity. When the mind drops the perception of duality there is neither duality nor unity. When one is firmly established in the oneness of the infinite consciousness, whether he is quiet or actively engaged in work, then he is considered to be at peace with himself.

— Yoga Vāsiṣṭha (tr. by Swami Venkatesananda, p.66)

The Vedas deal mainly with the subject of the three modes of material nature. O Arjuna, become transcendental to these three modes. Be free from all dualities and from all anxieties for gain and safety, and be established in the self.

— Bhagavad Gita 2.45