Understanding of the physiology of the heart from both a basic science and medical science perspective has been a life-time achievement for Arnold M. Katz, who has contributed significantly to both aspects of cardiovascular research. Among his ground-breaking achievements include his co-discovery of the phospholamban protein, which is critical in regulating calcium transport, as well as   his innovative contributions regarding contractile proteins in the heart. He has established a legacy where his knowledge of the cardiovascular system has permeated throughout medicine and basic science in a variety of forms including lectures, published journal articles, and books, in addition to his involvement in a vast number of societies, editorial boards, committees and fellowships. Arnold M. Katz was elected for a 3-year term as the President of the American section of the International Society of Heart Research, after being an integral part of it for more than 20 years in a variety of capacities including being a member of the board and on advisory committees. His involvement with the International Society of Heart Research contributed to promoting its influence and development in the world of cardiovascular sciences. In additional to being a reviewer for a number of high impact journals, including Nature, The New England Journal of Medicine, and Science, he has served on the editorial boards of the American Heart Journal, Circulation, and Circulation Research. He also was Editor-in-Chief of the Journal of Molecular and Cellular Cardiology for 6 years where he promoted its standards and impact factor among cardiovascular journals. In addition to his contribution to journals, he has also authored numerous books, including the Physiology of the Heart that is currently in press for its fifth edition. Arnold M. Katz understands the importance of teaching the future generation of cardiovascular scientists and clinicians which is reflected in his enthusiasm when interacting with the younger learning generation and stimulating their curiosity. He has received numerous Outstanding Teaching Awards, and served as the Chairman of numerous student award committees for the American Heart Association including the Summer Student Research Award, Young Investigators Award, and, most notably, the Louis N Katz Prize Committee, awarded to outstanding young investigators. In 1995 he was an Honoree for the AHA Young Investigator Award for Basic Research. The diversity of his accomplishments is exemplified by the variety of topics that he is knowledgeable in, including the history preceding modern medical science, specifically pertaining Ancient Greece and Hippocrates. The pervasiveness of Arnold M. Katz in cardiovascular sciences is reflected in his promotion of the scientific basis of the practice of cardiology on an international level. He highlighted the significance of biochemical and molecular mechanisms of cardiac dysfunction and brought it to the attention of investigators all over the world, predominantly through his numerous symposiums and invited lectures and professorships. His invaluable contributions to the cardiovascular field have caused him to be likened to a Pope of this area among his colleagues.