I consider it a great honour to be chosen as Thomas Lewis Lecturer of the British Cardiac Society. The work of Sir Thomas Lewis on the heart beat surely ranks as one of the outstanding achieve-ments in experimental physiology. I can claim a greater kinship to Thomas Lewis than that ofmerely being a distant admirer, for he can be regarded as the godfather of American cardiology. His stu-dents are to be found throughout the American continent where they have been instrumental in laying the foundation for the study of heart disease: White, Levine, Landis, Blumgart, and Bland in Boston; Oppenheim and Master in New York; Stroud in Philadelphia; Frank Wilson in Michigan; Katz in Chicago; Prinzmetal in Los Angeles; Graybiel in Florida-to name but a few. From Thomas Lewis they obtained above all else a scientific approach to medical experimentation. This displaced the then prevalent and shopworn ideas based on the subjectivity and the intuition of the chosen few. The hallmarks of Thomas Lewis's method of work were the application of precisely controlled and exacting methods, the assiduous gathering of evidence, the rigorous censorship of data, and the recognition of the role of animal ex-periments as a proper domain for inquiry intomany complex clinical problems. The yield of his legacy is not a harvest for a single season, and the rich fruit is still being gathered. This very lecture was initi-ated by his student and my teacher, Doctor Samuel A. Levine.