Do-re-mi comes from a medieval hymn to John the Baptist.
Around a thousand years ago, an Italian monk called Guido of Arezzo was tired of singers spending years memorising chant. He helped develop the musical staff and taught with syllables taken from a hymn whose lines each start one note higher: ut, re, mi, fa, sol, la. Ut later became do.
Guido was a Benedictine monk born around 991. Records of his life are scarce, coming mainly from two letters, and legends have gathered around him. What is clear is that at Pomposa Abbey, from about 1013, he grew frustrated at how long singers spent learning the chant repertoire by heart. He began developing a system of staff notation, writing music on lines so that pitches could be read rather than memorised, and gained a reputation for teaching music remarkably quickly.
Success bred resentment. His fellow monks felt threatened, and around 1025 he moved to Arezzo, where the bishop put him in charge of training the cathedral's singers. There he wrote the Micrologus, which became the most widely copied medieval treatise on music after Boethius. He claimed his methods cut the training of a cantor from ten years to one or two. Pope John XIX was intrigued enough to summon him to Rome, around 1028.
Guido's memory aid for singers came from the hymn 'Ut queant laxis'. Each of its first six half-lines begins on the next note up, and each starts with a syllable: ut, re, mi, fa, sol, la. Singers could learn the sound of each step by recalling the tune. Later, 'ut' was renamed 'do', usually credited to Giovanni Battista Doni, and a seventh syllable, 'si', was added from the initials of Sancte Iohannes, Saint John. In the 19th century the English teacher Sarah Glover changed 'si' to 'ti' so that every syllable began with a different letter, the form used in the song 'Do-Re-Mi'.
One popular credit is shakier. The Guidonian hand, a system for mapping notes onto the joints of the hand, is named after him, but Guido described only a rudimentary form, and the full system developed after his death.
Source: Wikipedia — Guido of Arezzo · Text summarised from Wikipedia (CC BY-SA 4.0)
