Bernardino Corio's late fifteenth-century history of Milan covers the city's past from its foundations to the collapse of the Sforza dynasty. Following the historiographic traditions established by Leonardo Bruni, its essential outlines are founded on careful use of sources and, for more recent events, contemporary memories and impressions. It is, however, also characterised by judicious revisionism and anecdotal invention. The careful reader always needs to ask why digressions have been included and what hidden points are being made. It is therefore well worth inquiring why Corio, a member of Duke Galeazzo Maria Sforza's court, chose to link his master's assassination on 26 December 1476 with a passage on his chapel choir and musical taste.