solmization

The designation of the musical scales by means of syllables, similar to modern tonic sol-fa. The notes of the Greek tetrachords were already designated by syllables, but Guido d'Arezzo in the 11th century replaced them by the hexachords and used the Latin syllables Ut, Re, Mi, Fa, Sol, La for their six notes. Si was added later for the seventh and Ut was replaced by Do in Italy and elsewhere, though it is still largely retained in France.

The syllables were derived from a hymn of the year 770 for the festival of St John the Baptist, the lines of the plainsong of which began on the successive notes of the hexachord: UT queant laxis; REsonare fibris; MIra gestorum; FAmuli tuorum; SOLve polluti; LAbii reatum; Sancte Ioannes. The seventh syllable, Si, was derived from the initial letters of the last line. These syllables, as in modern tonic sol-fa with movable Doh, were not immutably fixed to C, D, E, F, G, A, but could be transferred by mutation to other degrees of the scale, so long as the semitone always occurred between Mi and Fa. The so-called ‘natural hexachord’ beginning on C could thus be changed to the ‘hard hexachord’ beginning on G, in which case mi-fa corresponded with B–C, or to the ‘soft hexachord’ beginning on F (see hexachord).