Editing Music theory (section)

===Post-classical or Medieval Period===
{{see also|List of music theorists#Post-classical|List of medieval music theorists}}

====China====
The [[pipa]] instrument carried with it a theory of musical modes that subsequently led to the Sui and Tang theory of 84 musical modes.<ref name="Lam" />

====Arabic countries / Persian countries====

Medieval Arabic music theorists include:{{refn|See the [[List of music theorists#7th–14th centuries]], which includes several Arabic theorists; see also {{harvnb|d'Erlanger|1930–56|loc=1:xv-xxiv}}.|group=n}}

* Abū Yūsuf Ya'qūb [[Al-Kindi#Music theory|al-Kindi]] (Bagdad, 873&nbsp;CE), who uses the first twelve letters of the alphabet to describe the twelve frets on five strings of the [[oud]], producing a chromatic scale of 25 degrees.{{sfn|Manik|1969|loc=24–33}}
* [Yaḥyā ibn] al-[[Banu Munajjim|Munajjim]] (Baghdad, 856–912), author of ''Risāla fī al-mūsīqī'' ("Treatise on music", MS GB-Lbl Oriental 2361) which describes a [[Pythagorean tuning]] of the [[oud]] and a system of eight modes perhaps inspired by [[Ishaq al-Mawsili]] (767–850).<ref>{{harvnb|Wright|2001a}}; {{harvnb|Wright|2001b}}; {{harvnb|Manik|1969|loc=22–24}}.</ref>
* Abū n-Nașr Muḥammad [[Al-Farabi#Music|al-Fārābi]] (Persia, 872? – Damas, 950 or 951&nbsp;CE), author of ''[[Kitab al-Musiqa al-Kabir]]'' ("The Great Book of Music").<ref>Rodolphe d'Erlanger, ''La Musique arabe'', vol. I, pp. 1–306; vol. II, pp. 1–101.</ref>
* 'Ali ibn al-Husayn ul-Isfahānī (897–967), known as [[Abu al-Faraj al-Isfahani]], author of ''Kitāb al-Aghānī'' ("The Book of Songs").
* Abū 'Alī al-Ḥusayn ibn ʿAbd-Allāh ibn Sīnā, known as [[Avicenna]] (c. 980 – 1037), whose contribution to music theory consists mainly in Chapter 12 of the section on mathematics of his ''Kitab Al-Shifa'' ("[[The Book of Healing]]").{{sfn|d'Erlanger|1930–56|loc=2:103–245}}
* al-Ḥasan ibn Aḥmad ibn 'Ali al-Kātib, author of Kamāl adab al Ghinā' ("The Perfection of Musical Knowledge"), copied in 1225 (Istanbul, Topkapi Museum, Ms 1727).{{sfn|Shiloah|1964}}
* [[Safi al-Din al-Urmawi]] (1216–1294&nbsp;CE), author of the ''Kitabu al-Adwār'' ("Treatise of musical cycles") and ''ar-Risālah aš-Šarafiyyah'' ("Epistle to Šaraf").{{sfn|d'Erlanger|1930–56|loc=3:1–182}}
* Mubārak Šāh, commentator of Safi al-Din's ''Kitāb al-Adwār'' ([[British Museum]], Ms 823).<ref>Anon. LXII in Amnon Shiloah, ''The Theory of Music in Arabic Writings (c. 900–1900): Descriptive Catalogue of Manuscripts in Libraries of Europe and the U.S.A.'', RISM, München, G. Henle Verlag, 1979. See {{harvnb|d'Erlanger|1930–56|loc=3:183–566}}</ref>
* Anon. LXI, Anonymous commentary on Safi al-Din's ''Kitāb al-Adwār''.{{sfn|Ghrab|2009}}
* Shams al-dῑn al-Saydᾱwῑ Al-Dhahabῑ (14th century CE (?)), music theorist. Author of ''Urjῡza fi'l-mῡsῑqᾱ'' ("A Didactic Poem on Music").<ref name="Shiloah-2003">{{Cite book|title=The Theory of Music in Arabic Writings (c. 900–1900)|last=Shiloah|first=Amnon|publisher=G. Henle Verlag Munchen|year=2003|isbn=978-0-8203-0426-7|location=Germany|pages=[https://archive.org/details/sacredharp00buel/page/48 48, 58, 60–61]|url=https://archive.org/details/sacredharp00buel/page/48}}</ref>

====Europe====
The Latin treatise ''De institutione musica'' by the Roman philosopher [[Boethius]] (written c. 500, translated as ''Fundamentals of Music''{{sfn|Boethius|1989}}) was a touchstone for other writings on music in medieval Europe. Boethius represented Classical authority on music during the Middle Ages, as the Greek writings on which he based his work were not read or translated by later Europeans until the 15th century.{{sfn|Palisca and Bent|n.d.|loc=§5 Early Middle Ages}} This treatise carefully maintains distance from the actual practice of music, focusing mostly on the mathematical proportions involved in tuning systems and on the moral character of particular modes. Several centuries later, treatises began to appear which dealt with the actual composition of pieces of music in the [[plainchant]] tradition.<ref>{{harvnb|Palisca and Bent|n.d.|loc=Theory, theorists §5 Early Middle Ages}}: "Boethius could provide a model only for that part of theory which underlies but does not give rules for composition or performance. The first surviving strictly musical treatise of Carolingian times is directed towards musical practice, the Musica disciplina of Aurelian of Réôme (9th century)."</ref> At the end of the ninth century, [[Hucbald]] worked towards more precise pitch notation for the [[neume]]s used to record plainchant.

[[Guido d'Arezzo]] wrote a letter to Michael of Pomposa in 1028, entitled ''Epistola de ignoto cantu'',<ref>{{cite web|url=http://www.hs-augsburg.de/~harsch/gui_epi.html|title=Guy Aretini's letter to the unknown : modern translation of the letter|website=Hs-augsburg.de|access-date=3 March 2022}}</ref> in which he introduced the practice of using syllables to describe notes and intervals. This was the source of the hexachordal [[solmization]] that was to be used until the end of the Middle Ages. Guido also wrote about emotional qualities of the modes, the phrase structure of plainchant, the temporal meaning of the neumes, etc.; his chapters on polyphony "come closer to describing and illustrating real music than any previous account" in the Western tradition.{{sfn|Palisca and Bent|n.d.|loc=§5 Early Middle Ages}}

During the thirteenth century, a new rhythm system called [[mensural notation]] grew out of an earlier, more limited method of notating rhythms in terms of fixed repetitive patterns, the so-called rhythmic modes, which were developed in France around 1200. An early form of mensural notation was first described and codified in the treatise ''Ars cantus mensurabilis'' ("The art of measured chant") by [[Franco of Cologne]] (c. 1280). Mensural notation used different note shapes to specify different durations, allowing scribes to capture rhythms which varied instead of repeating the same fixed pattern; it is a proportional notation, in the sense that each note value is equal to two or three times the shorter value, or half or a third of the longer value. This same notation, transformed through various extensions and improvements during the Renaissance, forms the basis for rhythmic notation in [[European classical music]] today.