The life and music of Guillaume Dufay are among the most difficult to circumscribe for major Renaissance composers. One point of clarity is that Dufay was considered by far the leading composer of his day, a musician of almost unparalleled eminence, and one of the most famous men of his generation. Dufay's large and varied musical output, its extent only now coming into focus in some cases, acted to define the new musical style of the early-to-mid-fifteenth century and with it the course of Western music into the High Renaissance. Dufay's influence over musical composition was complete and permanent, affecting every genre and sphere. The singularity of his eminence can best be compared to that of Ludwig van Beethoven or perhaps Guillaume de Machaut, but in fact Dufay had the broader contemporary reputation.