Berlioz's Grand traité d'instrumentation et d'orchestration modernes, first published in 1844 with a second edition in 1855, is a classic textbook which has been widely read for over a century and a half by students, composers, historians and all who are drawn to Berlioz the musician or Berlioz the man. Like Rameau's Traité de l'harmonie it is a remarkable example of a great composer venturing into the world of technical and theoretical exposition and producing a masterpiece which affected the musical thinking of generations. In the nineteenth century Berlioz'sTreatise (as we shall hereafter call it) was read as a book of instruction; in the twentieth century it became a source book for anyone curious to learn more about the history of instruments and orchestral practice and a revealing exposure of Berlioz's musical thinking. His purpose in writing it was to guide composers towards a more expert and expressive use of instruments and to advise them of pitfalls that the unwary may encounter. This is explained in the book's introduction and again alluded to in the section on 'Other percussion instruments':

Our purpose in the present work is simply to study instruments which are used in modern music and to seek the laws which govern the setting up of harmonious combinations and effective contrasts between them while making special note of their expressive capabilities and of the character appropriate to each.

The study of an instrument's character and expressive potential was really more important to Berlioz than its range and technical limits, careful though he was to set out the latter in as clear a manner as possible. Practical information was already to be found in other treatises and in the separate 'Méthodes' available for every instrument, so there was a special urgency in conveying his personal understanding of colour and timbre, couched in the notion of continuity and tradition from Gluck through Spontini, Beethoven and Weber to the present day. 'Harmonious combinations and effective contrasts' are treated in the chapter on the orchestra, so that the novice composer may learn the essentials of orchestration from a study of . . .