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.
Atheistic existentialism
Albert Camus writes of dualisms—between happiness and sadness—as well as life and death. In "The Myth of Sisyphus", such dualism becomes paradoxical because humans greatly value their existence while at the same time being aware of their mortality. Camus believes it is human nature to have difficulty reconciling these paradoxes; and indeed, he believed humankind must accept what he called "the Absurd". On the other hand, Camus is not strictly an existential atheist because the acceptance of "the Absurd" implies neither the existence of God nor the nonexistence of God (compare agnosticism).