In his thorough analytical study of Beethoven's Piano Sonata in E, Op. 109, Nicholas Marston suggests a unique way of understanding this important work. The book provides an exhaustive study of its sources and an analytical approach to the structure of the sonata itself. The source study is based on a complete transcritpion of all the surviving manuscript sources for the work; the book includes a large majority of the sketches, and parts of the autograph score.The introductory chapter reivews Heinrich Schenker's work on Op. 109. In Chapter 2 Beethoven's letters, conversation books, sketchbooks and other sources are used to build up a detailed picture of the progess of his work on the sonata. The middle chapters form the core of the analytical study in which the sketches for each part of the three movements are analysed in detail, and the relevance of the sketches to the final version is explored. The final chapter extends the notion of 'sketch' beyond Op. 109 and summarizes the results of the study. No stone is left unturned: even Beethoven's previously misunderstood notation of final barlines in the autograph score is shown to be of structural significance.The book is important in several respects. The attitude adopted towards the sketches is postive , approaching them as valid compositional acts and not wrong turnings en route to a perfect final version. As an analytical study the book provides perhaps the most extended Schenkerian analysis of a Beethoven sonata yet published, and offers a rare Schenkerian analysis of a variation movement. It may equally be read as a extension or critique of Schenkerian thinking: it goes beyond Schenker both in its espousal of unconventional 'background' strucures and in its suggestion of a single structural plan for the entire three-movement work.