Māndukya 2.09

If the universe with its five fold differences is understood clearly, it would certainly cease to exist; there is no doubt. This duality is merely an illusion; in reality, it is non-dual.

Bhāshya 2.09

'paramārthataḥ' - '(seeing oneself as different) from the Supreme Lord'; 'dvaitaṃ' - means knowing in two ways, i.e. knowing the Supreme differently by the ignorant; 'advaita' - understanding the supreme as not otherwise, i.e. understanding the Supreme AS-IS. The relationship between the body and its owner is merely an illusion of the embodied being arising out of pride. In truth, this does not exist, as everything is under the control of the Supreme Lord.

"The relationship between the body and its owner is merely an illusion of the embodied being. In truth, this does not exist, as everything is under the control of the Supreme Lord. This is perceived due to pride, beginning with the body. If there is an acceptance of his supreme existence, then, through divine knowledge, he would undoubtedly turn back."

- stated thus in the ancient testimonial named Brahmatarka, the reasoning of Brahman.

The term 'advaita' i.e. Non-duality, is understanding not otherwise, i.e. understanding AS-IS. It involves knowledge of the supreme reality and others. The term 'dvaitaṃ', i.e. duality, means knowing in two ways, i.e. knowing differently by the ignorant. The word 'paramārthataḥ' in this context means '(seeing oneself different) from the Supreme Lord'. By his will alone, of him, illusion is created. Thus the knowledge of wrongly perceiving Him and the reality comes from Him, and by His will alone it ceases.

"The supreme Brahman, not clearly known in dual ways, is indeed the non-dual supreme Brahman known otherwise. The soul indicates duality as false knowledge, stemming from the ultimate reality, born of Vishnu's desire and control. Illusion is thus merely illusion, originating due to supremacy for the supreme purpose. He, the Lord Vishnu, is imperishable. Illusion is described as desire, and its origin is mere illusion. Because of his superiority, Lord Vishnu, the imperishable, exists for the benefit of others."

- stated thus as well.