Many of the great discoveries and developments in the sciences and the arts were made by people who were 'mentally different'. Some such pioneers or innovators had experiences that were indistinguishable from the phenomena defined as mental illness (or madness). It has been argued that such experiences are a necessary constituent of the creative process, and that this may apply to the sciences as much as to the arts. Increasingly, scientists propose a means by which it may be possible to identify (and eliminate) the factors that influence the altered states associated with mental illness. This may be an appropriate time to review the cultural and social significance of all forms of 'madness', especially in the light of emerging models of psychiatric nursing practice.