Since its publication, Existence has been regarded as the most important, complete, and lucid account of the existentialist approach to psychology. From the works of the leading spokesmen of the existential analytic movement, the editors have selected classic case histories and other writings to define the approach that seeks to understand mental illness, in the words of Rollo May, "... not as deviations from the conceptual yardstick of this or that psychiatrist... but as deviations in the structure of the particular patient's existence, the disruptions of his condition humane. "