For half a century Henle's edition of the Beethoven sonatas - the ''New Testament'' of the piano repertoire - has been universally recognized as the standard starting-point for any serious study of these works. Now, with the publication of the three op. 31 sonatas in revised separate editions, we are raising the yardstick another notch: no less a musician than the pianist and conductor Murray Perahia has agreed, for the first time ever, to publish his fingerings and, as co-editor, to confide his profound insights into the sources to music lovers everywhere. The musical text has been prepared in strict accordance with the rules of modern Urtext editing, and the volume is rounded off with a lengthy and informative preface and detailed notes on sources and alternative readings.