A theory of emotional expression, ignored since 1906, holds that facial muscles act as ligatures on facial blood vessels and thereby regulate cerebral blood flow, which, in turn, influences subjective feeling. The theory, developed by Israel Waynbaum, a French physician, hypothesizes the subjective experience of emotions as following facial expression rather than preceding it. It answers Darwin's question of why different muscles contract or relax in different emotions better than Darwin's own theory. When restated in terms of contemporary neurophysiological knowledge, it explains and organizes several ill-understood emotional processes and phenomena.