The Cantigas are written in the early Medieval Galician variety
Galician-Portuguese, using Galician spelling; this was because of Galician-Portuguese being fashionable as a lyrical language in
Castile at the time, as well as Alfonso X having passed part of his early years in Galicia and so probably being a fluent speaker since his childhood.
The Cantigas are a collection of 420 poems, 356 of which are in a narrative format relating to Marian miracles; the rest of them, except an introduction and two prologues, are of songs of praise or involve Marian festivities. The Cantigas depict the Virgin Mary in a very humanized way, often having her play a role in earthly episodes.
The authors are unknown, although several studies have suggested that
Airas Nunes might have been the author of a large number of the Cantiga poems. King Alfonso X — named as Affonso in the Cantigas — is also believed to be an author of some of them as he refers himself in first person. Support for this theory can be found in the prologue of the Cantigas. Also, many sources credit Alfonso owing to his influence on other works within the poetic tradition, including his introduction on religious song. Although King Alfonso X's authorship is debatable, his influence is not. While the other major works that came out of Alfonso's workshops, including histories and other prose texts, were in
Castilian, the Cantigas are in Galician-Portuguese, and reflect the popularity in the Castilian court of other poetic corpuses such as the
cantigas d'amigo and cantigas d'amor.
The metrics are extraordinarily diverse: 280 different formats for the 420 Cantigas. The most common are the
virelai and the
rondeau. The length of the lines varies between two and 24 syllables. The narrative voice in many of the songs describes an erotic relationship, in the troubadour fashion, with the Divine. The music is written in notation which is similar to that used for chant, but also contains some information about the length of the notes. Several transcriptions exist. The Cantigas are frequently recorded and performed by
Early Music groups, and quite a few CDs featuring music from the Cantigas are available.
Musicians playing the Spanish vihuela.
The Cantigas are preserved in four manuscripts:
 To (códice de Toledo, Biblioteca Nacional de España, MS 10069), T (Biblioteca de
El Escorial, MS T.I.1), F (códice de Florencia,
Florence, Biblioteca Nazionale, MS b.r. 20) and E (códice de los músicos, Biblioteca de
El Escorial MS B.I.2). E contains the largest number of songs (406 Cantigas, plus the Introduction and the Prologue); it contains 41 carefully detailed miniatures and many illuminated letters. To is the earliest collection and contains 129 songs. Although not illustrated, it is richly decorated with pen flourished initials, and great care has been taken over its construction. The T and F manuscripts are sister volumes. T contains 195 surviving cantigas (8 are missing due to loss of folios) which roughly correspond in order to the first two hundred in E, each song being illustrated with either 6 or 12 miniatures that depict scenes from the cantiga. F follows the same format but has only 111 cantigas, of which 7 have no text, only miniatures. These are basically a subset of those found in the second half of E, but are presented here in a radically different order. F was never finished, and so no music was ever added. Only the empty staves display the intention to add musical notation to the codex at a later date. It is generally thought that the codices were constructed during Alfonso's lifetime, To perhaps in the 1270s, and T/F and E in the early 1280s up until the time of his death in 1284.
The musical forms within the Cantigas, and there are many, are still being studied. There have been many false leads, and there is little beyond pitch value that is very reliable. Mensuration is a particular problem in the Cantigas, and most attempts at determining meaningful rhythmic schemes have tended, with some exceptions, to be unsatisfactory. This remains a lively topic of debate and study. Progress, while on-going, has nevertheless been significant over the course of the last 20 years.