The present account includes a brief life history of Walter Rudolf Hess (1881-1973) and a review of his major neurophysiological contributions. Hess belonged to the nearly extinct generation of great universalists among students of human physiology. He began his scientific work in hemodynamics and ophthalmology, then studied the functional organization and regulation of circulation and respiration and developed a number of highly sophisticated instruments which fostered his international reputation. By electrically stimulating the brain of the unanesthetized, freely moving animal he explored the functional organization and localization of the cat diencephalon in terms of autonomic, extrapyramidal motor functions, and instinctive behavior, e.g. hunger, thirst, fear, and rage. His thoughts on biological order led him to consider the problems of psychic forces. He was convinced of the close correlation of behavioral research and neurophysiology and believed that neuronal patterns determine the content of consciousness without providing clues concerning the transformation of such patterns into subjective experience.