The Treatise on Harpsichord Tuning was the first French document to discuss keyboard performance practice in any detail. Jean Denis was both a harpsichord builder of renown and the organist of a prominent Parisian church, and is thus an authority worthy of careful study. The treatise addresses numerous matters of interest to both scholars and performers, including temperament, ornamentation, fugue, and the use of the organ in liturgical practice. Also included in the treatise are a keyboard prelude designed to reveal errors in tuning, and two delightful anecdotes attesting to the power of music. The forthright character of Denis’s writing lends a unique and distinctly enjoyable tone to the work.