Philosophy of mind
Dualism is a set of views about the relationship between mind and matter (or body). It begins with the claim that mental phenomena are, in some respects, non-physical. One of the earliest known formulations of mind–body dualism was expressed in the eastern Sankhya and Yoga schools of Hindu philosophy (c. 650 BCE), which divided the world into purusha (mind/spirit) and prakriti (material substance). Specifically, the Yoga Sutra of Patanjali presents an analytical approach to the nature of the mind.
Nondualism
A modern strand of thought sees "nondual consciousness" as a universal psychological state, which is a common stratum and of the same essence in different spiritual traditions. It is derived from Neo-Vedanta and neo-Advaita, but has historical roots in neo-Platonism, Western esotericism, and Perennialism. The idea of nondual consciousness as "the central essence" is a universalistic and perennialist idea, which is part of a modern mutual exchange and synthesis of ideas between western spiritual and esoteric traditions and Asian religious revival and reform movements.