Editing Accidental (music) (section)

== History of notation ==
The three principal symbols indicating whether a note should be raised or lowered in pitch are derived from variations of the small letter&nbsp;''b'':<ref>[[Frederick Niecks|Niecks, Frederick]]. ''The Flat, Sharp, and Natural. A Historical Sketch''. Proceedings of the Musical Association, 16th Sess., (1889&nbsp;-&nbsp;1890), pp. 79–100.[https://www.jstor.org/pss/765359 (JSTOR)]</ref> the [[sharp (music)|sharp]] ({{music|sharp}}) and [[natural (music)|natural]] ({{music|natural}}) signs from the square "[[b quadratum]]", and the [[flat (music)|flat]] sign ({{music|flat}}) from the round "[[b rotundum]]".

The different kinds of B were eventually written differently, so as to distinguish them in music theory treatises and in notation. The flat sign {{music|flat}} derives from a round ''b'' that signified the soft hexachord, ''hexachordum molle'', particularly the presence of B{{music|flat}}. The name of the flat sign in French is ''bémol'' from medieval French ''bé mol'', which in modern French is ''bé mou'' ("soft b"). The natural sign {{music|natural}} and the sharp sign {{music|sharp}} derive from variations of a square ''b'' that signified the hard hexachord, ''hexachordum durum'', where the note in question is B{{music|natural}}. The name of the natural sign in French is ''bécarre'' from medieval French ''bé quarre'', which in modern French is ''bé carré'' ("square b"). In German music notation, the letter ''B'' or ''b'' always designates B{{Music|flat}} while the letter ''H'' or ''h'' – a deformation of a square ''b'' – designates B{{Music|natural}}.

In the [[High Middle Ages]], a widespread musical tradition was based on the [[hexachord]] system defined by [[Guido of Arezzo]].<ref>Guido d'Arezzo, "Epistola de ignotu cantu [ca. 1030]", abridged translation by Oliver Strunk in Source Readings in Music History, selected and annotated by Oliver Strunk, 5 vols. (New York: W. W. Norton, 1965): 1:121–25. Latin text in Martin Gerbert, Scriptores ecclesistici de musica sacra potissimum, 3 vols. (St. Blasien, 1784), 2:43–46, 50. See also Clause V. Palisca, "Introduction" to Guido's Micrologus, in Hucbald, Guido, and John on Music: Three Medieval Treatises, translated by Warren Babb, edited, with introductions by Claude V. Palisca, index of chants by Alejandro Enrique Planchart, 49–56, Music Theory Translation Series 3 (New Haven and London: Yale University Press, 1978): esp. 49–50. {{ISBN|0-300-02040-6}}.</ref> The basic system, called ''musica recta'', had three overlapping hexachords. Change from one hexachord to another was possible, called a ''mutation''. A major problem with the system was that mutation from one hexachord to another could introduce intervals like the [[tritone]] that musicians of the time considered undesirable. To avoid the dissonance, a practice called [[musica ficta]] arose from the late 12th century onward. This introduced modifications of the hexachord, so that "false" or "feigned" notes could be sung, partly to avoid dissonance. At first only B could be flattened, moving from the ''hexachordum durum'' (the ''hard hexachord'') G–A–B–C–D–E where B is natural, to the ''hexachordum molle'' (the ''soft hexachord'') F–G–A–B{{music|flat}}–C–D where it is flat. The note B is not present in the third hexachord ''hexachordum naturale'' (the ''natural hexachord'') C–D–E–F–G–A.{{Citation needed|date=March 2014}}<!-- This ought to be combined with following paragraph -->

Strictly speaking the medieval signs {{music|natural}} and {{music|flat}} indicated that the melody is progressing inside a (fictive) ''hexachord'' of which the signed note is the ''mi'' or the ''fa'' respectively. That means they refer to a group of notes ''around'' the marked note, rather than indicating that the note itself is necessarily an accidental. For example, when a semitone relationship is indicated between F and G, either by placing a mi-sign ({{music|natural}}) on F or a fa-sign ({{Music|flat}}) on G, only the context can determine whether this means, in modern terms, F{{Music|sharp}}-G or F-G{{Music|flat}}, or even F{{Music|flat}}–G{{Music|doubleflat}}. The use of either the mi-sign on F or the fa-sign on G means only that "some kind of F goes to some kind of G, proceeding by a semitone".<ref>Margaret Bent, "Diatonic ''Ficta''", ''Early Music History'' 4 (1984): pp.&nbsp;1–48. Citation on pp.&nbsp;14–15.</ref>

As polyphony became more complex, notes other than B required alteration to avoid undesirable harmonic or melodic intervals (especially the augmented fourth, or [[tritone]], that music theory writers referred to as ''diabolus in musica'', i.e., "the devil in music"). Nowadays "ficta" is used loosely to describe any such un-notated accidentals. The implied alterations can have more than one solution, but sometimes the intended pitches can be found in lute [[tablature]]s where a fret is specified.<ref>{{Cite book|url=https://books.google.com/books?id=v5Oz7vPCQXoC&q=lute+tablatures+where+a+fret+is+specified+ficta&pg=PA190|title=Music History During the Renaissance Period, 1520-1550: A Documented Chronology|last=Gangwere|first=Blanche|date=2004|publisher=Greenwood Publishing Group|isbn=978-0-313-29248-4|language=en}}</ref>

The convention of an accidental remaining in force through a measure developed only gradually over the 18th century. Before then, accidentals only applied to immediately repeated notes or short groups when the composer felt it was obvious that the accidental should continue.<ref>{{cite encyclopedia|year = 1972|title = Accidentals|encyclopedia = Harvard Dictionary of Music|publisher = Harvard University Press|edition = 2nd}}</ref> The older practice continued in use well into the 18th century by many composers, notably [[Johann Sebastian Bach]].<ref>Anthony Pryer, "Accidental", ''The Oxford Companion to Music'', edited by Alison Latham (Oxford University Press, 2002).</ref> The newer convention did not achieve general currency until early in the 19th century.<ref>Don Michael Randel, "Accidental", ''The Harvard Dictionary of Music'', fourth edition (Harvard University Press, 2003). {{ISBN|978-0-674-01163-2}}; Ian D. Bent, David W. Hughes, Robert C. Provine, Richard Rastall, Anne Kilmer, [[David Hiley]], Janka Szendrei, Thomas B. Payne, Margaret Bent, and Geoffrey Chew, "Notation", ''The New Grove Dictionary of Music and Musicians'', second edition, edited by [[Stanley Sadie]] and [[John Tyrrell (musicologist)|John Tyrrell]] (London: Macmillan Publishers, 2001): §III, 4 (vi).</ref>