Traité de l'expression musicale

Mathis Lussy (1828-1910) was a Swiss music theorist who taught that rhythm was the foundation for expressive musical performance. In *Traité de l’expression musicale* he literally wrote the book on musical expression. He believed that the best composers intuitively followed the rules that Lussy codified, and that even inexpressive performers could become somewhat more expressive by understanding and following the rules in the book.