In Advaita Vedānta, adhyāsa, or superimposition, is the fundamental error by which the qualities of one thing are mistakenly attributed to another. It is described as a mutual superimposition of the Self (Ātman) and the non-self (anātman): the attributes of body, mind, and world are projected onto the pure Self, and the existence and consciousness of the Self are, in turn, projected onto these transient entities. Śaṅkara characterizes this as the apparent presentation of something previously experienced in a different context, such that one thing is taken to be another due to incomplete knowledge. Classic illustrations include mistaking a rope for a snake or a shell for silver, where what appears is not actually present, yet is taken as real.

This superimposition is said to be beginningless (anādi), rooted in ignorance (avidyā), and is regarded as the basic cognitive error that gives rise to saṃsāra, the cycle of birth and death characterized by suffering and bondage. Because of adhyāsa, the body and mind are taken to be the Self, so that birth, death, pleasure, pain, doership, and enjoyership are all imputed to pure consciousness. At the same time, inert entities such as the body and mind are treated as if they possessed independent reality and consciousness, as though they were truly “I.” In this way, adhyāsa generates the illusion of duality and multiplicity where, according to Advaita, only non-dual Brahman truly exists.

Spiritual practice in this tradition is oriented toward recognizing the falsity of this superimposition through discriminative knowledge (viveka) and right understanding (jñāna). When ignorance is dispelled by direct knowledge of Brahman/Ātman, the mutual superimposition of Self and non-self ceases, and the non-dual nature of reality is recognized. Liberation (mokṣa) is thus not the acquisition of something new, but the removal of the veil of adhyāsa that made the ever-free Self appear bound.