Acharya Prashant explains that the very existence of an individual as a 'living being' constitutes duality. Duality is the fundamental state where a subject perceives an object, and one's existence is defined by time, space, and the presence of 'the other.' In this state, the observer always seeks something from the observed, creating a relationship similar to that of a thirsty person and water. The speaker clarifies that while duality is our factual reality, non-duality is our ultimate truth. The mind constantly wanders in duality, seeking the peace and security that only non-duality can provide, yet it remains trapped because it tries to find truth while preserving its own ego.