This thesis argues that the disciplines of comparative philology and linguistics exerted significant force on the priorities and techniques of musicologists and composers in fin-de-siècle France, and examines how ideologies of Indo-Europeanism (or aryanism), concomitant with comparative philology, generated efforts to ‘sound out’ Indo-Europeanism in music. Using a relational approach, dense interdisciplinary networks of philologists/linguists, musicologists, and composers are reconstructed to demonstrate how musicological appropriations of linguistic research reverberated in musical composition right through the 1950s. These contexts reveal how wide-ranging repertories emerged from ethnic-nationalist projects of reclaiming Indo-European ‘patrimony’.

The thesis is in two Parts. Part I, ‘Philologie comparée, musicologie, and Indo-European hypotheses’, is organised around four overlapping intellectual networks comprising comparative philologists and musicologists. Francophone musicologists’ efforts to model their discipline on that of comparative philology are surveyed. Scholars discussed include Fétis, Gevaert, Bourgault-Ducoudray, Burnouf, Meillet, Aubry, Emmanuel, and Grosset. Arguments concerning the place of music between concepts of ‘language’ and ‘race’ are retraced, with special attention paid to musicologists’ efforts to pinpoint quasi-morphological ‘Indo-European’ musical structures – in particular, ‘modes’ and ‘metres’ – construed as ‘essential’ and ‘ancestral’.

Part II, ‘Composing with philology: performances of authenticity and innovation’, describes how the intellectual project elaborated in Part I infiltrated compositional practices. Close musical and paratextual readings show how composers legitimated experimentalism through ‘performances’ of philological ‘authenticity’. Over time, musical parameters such as modes and metres are abstracted and assimilated into compositional lexicons. Composers discussed include Bourgault-Ducoudray, Saint-Saëns, Séverac, Roussel, and Emmanuel. This root system flourishes in the music of Olivier Messiaen, whose rhythmic technique is revisited in light of manuscript materials. From his borrowings of early Indian metres (deśītālas) through his hyperformalist ‘Mode de valeurs et d’intensités’, Messiaen’s rhythmic style is radically reinterpreted as a logical extension of francophone musicology’s disciplinary and epistemological inheritance from comparative philology.