The theory of musical topoi (or topics) has emerged in recent decades as a powerful tool for the analysis of musical expression within tonal repertories. Largely originating in Leonard Ratner’s ground-breaking treatise Classic Music from 1980, it has since been considerably developed and extended by some of his students, especially Wye Allanbrook and Kofi Agawu. The theory has also stimulated considerable interest from music semioticians such as Robert Hatten, Márta Grabócz and Raymond Monelle, who find it a major resource for the investigation of extra-musical referentiality and meaning. Indeed, topical analysis may well be considered one of the success stories of modern musicology.