During my thirty-five years of experience as a hospital physician and in private I have watched with special interest the fate of the numerous cases of endocarditis which came under my charge, endeavouring as far as possible to trace the later history of such cases for a lengthened period. During the earlier years I merely treated the rheumatism, believing, as I had been taught, that little or nothing could be done to prevent disaster to the heart. I had the pain of discovering that many, indeed most, of these cases merged into permanent valvular disease. This distressing experience induced me to experiment on various methods of preventive treatment. Of these, one has proved successful and has been constantly employed by me for twenty years. The work of the Rheumatic Heart must for a time be minimised The method is very simple; it is merely to give the heart the same advantages, the same opportunities for repair, so far as we can, that the joints enjoy; in other words, by every means in our power we lessen the work to be done by the heart. The most absolute quiet is enjoined, the patient lies with his head at a low level, pain and fever are subdued, no excitement is permitted, the patient is made as comfortable as we can make him, and sleep is encouraged—in fact, we seek to attain physiological rest. We follow the precept of our ancient Egyptian brother, declared so many thousand years ago: we give the ailing heart the nearest approach to rest that is practicable. In addition we administer sodium or potassium iodide, partly to help in the absorption of morbid exudations but chiefly to lower vascular tension, just as we give these drugs in cases of internal aneurism. Lastly, we endeavour to influence the cardiac vasomotor and trophic nerves reflexly by gentle and almost painless stimulation of those cutaneous nerves which we know from physiological data, and from the evidence of the referred pains of angina to be in close relation with the heart—viz., the first four dorsal nerves. I believe, however, that by far the most important factor in the abortive treatment of endocarditis is rest, rest for many weeks, the slowing of the heart, the lengthening of the diastole, which is the only rest-time possible, the careful avoidance of high blood pressures, which the weakened and softened valve cusps cannot sustain without peril, and the diminution of the volume of the blood to be moved. Only then, when functional activity is minimised, can we hope for repair of mischief, re-formation of destroyed endothelia and absorption of effusion in the valve cusps. Moreover, repair is only possible during the early stages of endocarditis; later the mischief is permanent, unalterable by any form of treatment. The method fails if from any reason it is found impracticable to slow down the heart, for example, if asthma, bronchitis, or pneumonia, or great nervous excitability co-exist.