For 11 voices in 3 choirs instruments and continuo.The Scala Aretina is Valls' best-known work taking its name from the Guidonian hexachord upon which it is constructed. The mass gave rise to one of the most contested controversies in the history of music: in the Qui Tollis of the Gloria the entry of the 2nd choir soprano forms an unprepared ninths - certainly an infringement of the rules of harmony. This sparked off an unprecedented battle among Spanish musicians as to the value of rules in musical composition and the value of pleasing the ear as an aesthetic principle as opposed to artistic freedom.
