Years after Walter Piston's death, his students and their students can still take great pride in the enduring vitality of his teaching. By now it is plain that the book is different from what it used to be, but its essential approach and its basic substance remain as they were. The major departure of the fourth edition was the addition of seven new chapters, including four on the complicated subject of harmony after common practice, which had not been discussed in the first three editions.However, then as now, the core of the book remains the exhaustive treatment of common-practice harmony, the subject of most one-year or two-year courses in tonal harmony. In the present edition, the entire text has been carefully revised with a view to clarifying the language and illuminating the essential principles. Wherever possible, the text has been "opened up" to allow the reader to adopt a more leisurely pace through what had been a terse and detailed presentation. The results will also be perceived in the more spacious design of this edition. New exercises have been added to the early chapters as well as some fresh music examples. There is an entirely new chapter on musical texture that serves to clear up many difficult points encountered by the beginning student. Another innovation is the rearrangement of the chapters dealing with harmonic rhythm and the structure of the phrase as well as the inclusion of a short summary of analytical method. This book has long been known as an introductory textbook, but because of its comprehensive range, it also serves as an invaluable reference book. The acquisition of an consummate knowledge of composers' practice'”the goal of any study of harmony'”is admittedly an endless assignment. Ars longa, vita brevis , but consolation may be derived from the thought that intellectual and artistic rewards are to be found at all stages along the way.