The Advaita Vedānta philosophy, the chief exponent of which was Śaṅkara (A.D. 788-820), accepts Brahman (the Absolute), which is beyond names, forms, attributes, and hence, defies all description, as the Ultimate Reality. But the world that we perceive with its myriad names, forms and attributes, circumscribed by time, space and causation, cannot be easily brushed aside or wished away. Hence there is a great need to explain the relationship between Brahman the Absolute and this world of phenomena. ‘Adhyāsa’ or ‘adhyāropa’ is the explanation offered by Advaita Vedānta.

Literally, the word means one thing ‘sitting upon’ another, hiding its nature for the time being. It is defined as ‘the appearance elsewhere, as in memory, of something perceived earlier.’ (Adhyāsa-bhāṣya of Śaṅkara, Brahmasūtras 1.1.1). Two oft-repeated analogies are the erroneous perception of a snake in a rope in insufficient light and of silver in nacre shining in light. In both cases, the impressions of a snake and silver from an earlier idea of the same are superimposed on the rope and the nacre under conditions conducive to the erroneous perception. These erroneous perceptions have been caused by the ‘adhyāsa’ of the snake on the rope and the silver on the nacre. This again is due to ajñāna or avidyā (ignorance) of the real nature of the adhiṣṭhāna (substratum—here, the rope and the nacre). This ajñāna is anādi (without beginning) since it has no ascertainable beginning. Once this ajñāna is removed by right perception, the error disappears automatically.

Using the doctrine of adhyāsa and the two analogies already mentioned, Advaita metaphysics tries to explain that the world palpably perceived by the senses is only an erroneous perception caused by adhyāsa on Brahman. Once the real nature of Brahman is realised, the world appearance ceases. At the subjective level, this adhyāsa causes the erroneous perception of the body-mind complex on the ātman (the immanent aspect of Brahman at the individual level). Once the real nature of the ātman is realised, its identification with the body-mind complex will disappear.