Just what might be "the nature and the cause" of angina pectoris has been a subject of interest and of varied opinion from the time of Heberden. Huchard, in the last quarter of the last century, listed some sixtythree various theories as to the cause. This list covered the possibilities so thoroughly that the only addition since that time has been that ascribing the source of pain to the esophagus and stomach—and not to the heart at all. Each theory has won adherents in its time, only to lose them again and then to rewin them in later decades. Each theory has had as its exponents some of the most distinguished physicians of the period. It may be said of angina pectoris in general what W. Townsend Porter said of the experimental work on the coronaries: "Seldom have the results of physiological studies been more at variance. The attentive reader