"A dualist acknowledges a fundamental distinction between matter and mind. A monist, by contrast, believes that mind is a manifestation of matter - material in a brain or perhaps a computer - and cannot exist apart from matter. A dualist believes the mind is some kind of disembodied spirit that inhabits the body and therefore conceivably could leave the body and exist somewhere else. Dualists readily interpret mental illness as 'possession by devils,' those devils being spirits whose residence in the body is temporary, such that they might be 'cast out.' Dualists personify inanimate physical objects at the slightest opportunity, seeing spirits and demons even in waterfalls and clouds."