Eleventh century Benedictine monk Guido d'Arezzo is credited with developing the system of music notation in which the lines and spaces of a staff indicate specific pitches. The names he assigned to the pitches -- ut (later changed to do), re, mi, fa, sol, and la -- are known to be derived from the first syllable of the lines of an eighth century poem, "Ut queant laxis," by Paul the Deacon. In d'Arezzo's version, each line begins on a successively higher note of the scale. In his 2007 book Horace's Odes and the Mystery of Do-Re-Mi, published by Oxbow Books, Stuart Lyons argues that d'Arezzo did not compose the melody used with the poem, as has generally been assumed, but used a melody written by first century BCE Roman poet Horace for one of his own Odes. Lyons, an expert on Horace, asserts that the poet's original melody was preserved in a tenth century manuscript, and d'Arezzo applied the melody to Ut queant laxis. This eight-minute CD, The Mystery of Do-Re-Mi, was created as an audio supplement to the book. Baritone Christopher Gabbitas and lutenist David Miller perform Horace's ode in Latin and English, as well as Ut queant laxis. Based on the brief program notes, it's impossible to assess the authority of Lyons' argument, which raises more questions than it answers. (Given the inexact nature of notation in the tenth century, how can we know exactly what the melody was? How can we know that Horace, in fact, was the composer of the melody? If he was, how was it transmitted over the millennium between its composition and its notation? Is there evidence that d'Arezzo would have had access to the manuscript containing the poem and melody?) In any case, it's a fascinating musicological mystery that should be of interest to anyone intrigued by the roots of notated music and the complex relationship between music itself and the ways in which it is inscribed.