Although the remarks that follow are based can be induced in a completely healthy heart by a relatively minor perturbation, on my reading not of the volume itself, but on my reading of the table of contents and namely, an electrical stimulus delivered in the vulnerable period. On the other hand, it of the editors' comments on each of the main sections of the book, it is clear that this is a very rare event, since during a lifetime synthesis is a timely one that shows how of 70 years, the average human heart con- much we have learned in the past 30 years tracts and relaxes some 2. 5 billion times about tachyarrhythmias. This book also sets without developing persistent ventricular the stage for further research. New insights fibrillation. That an event so easily induced into the cellular basis for the generation of in a normal heart should occur so rarely is arrhythmias, new studies of fibrillation, an intriguing fact that seems worth bearing deeper investigations of the role of the ner- in mind as we continue to investigate this fascinating phenomenon.