The tangible reward of clinical surgery is that with our own hands we change the course of disease and so improve and prolong our patients' lives. That is what we find so compelling. From earliest times the goals of surgery were to staunch haemorrhage, to relieve obstruction and to drain pus. These simple tasks remain the most dramatically effective things we do. Every time we save a patient who is bleeding to death from a simple stab wound or a complex aneurysm; or when we relieve obstruction of a coronary artery, a heart valve, the oesophagus or trachea; and when we drain an empyema and see the improvement in a sick and toxic patient within hours, it is our knowledge, our skill and our craft that benefit the patient. These treatments are based on our knowledge of anatomy, physiology, pathology and the natural history of disease. We apply our knowledge in a rational and logical way; we see a direct cause and effect between what we do and the benefit we give.