Book excerpt: Originally published in 1963 and with a foreword by Yehudi Menuhin, this book begins with a study of the historical scene and the conditions under which Bach and his player colleagues lived, wrote and worked. It discusses the instruments then in use and required by Bach in these compositions and why certain passages in consequence took the shape or form they did. The book analyses Bach’s music and demonstrates how he built up whole movements from a single 3 or 4-note germ, and at the same time shows how the composer developed his own powers. How, for example, in addition to making any necessary changes to overcome technical deficiencies, he began to think about the musical suitability of passages given to certain instruments instead of just giving the same passage to any of the instruments he happened to have included in his concertante group. When it was first published the book was believed to be the only one in English to deal with the subject in such detail.