to the crown, since the Partidas established the right of representation in the succession to the throne. Without taking away from the preceding argument, the Partidas undoubtedly acquired legal force under Alfonso XI, upon being incorporated in the orden de prelación by the first law of article 28 of the Ordenamiento de Alcalá of 1348. This fact is considered by those authors who do not believe that the Partidas was enacted by Alfonso X as a "late enactment". Sources The Siete Partidas can be characterised as a text of civil law or ius commune (based on Justinian Roman law, canon law, and feudal laws), alongside influences from Islamic law. Its sources were diverse. Among the most important were the Corpus Iuris Civilis of Justinian; the works of the Roman glossators and commentators, for example Franciscus Accursius and Azzus; canon law texts like the Decrees of Gregory IX and the work of Saint Raimundo de Peñafort; the Islamic legal treatise Villiyet written in Islamic Spain; and some Castilian fueros and customs. Other sources include philosophical works by Aristotle and Seneca; the Bible and texts by the Church Fathers; works by Isidore of Seville and Thomas Aquinas; the Libri Feudorum (compilation of Lombardic feudal law); the Roles D´Olerons (a collection of writings on commercial law); the Doctrinal de los juicios (Trial Manual) and the Flores de Derecho (Flowers of law) by Maestro Jacobo, who also worked on the Partidas; and the Margarita de los pleytos by Fernando Martínez de Zamora. Structure and content The Partidas brings together all the jurisprudence of the era into a single, unified vision, and for that reason has been regarded as a summa de derecho (the highest and binding authority for deciding legal issues). It deals, among other things, with constitutional law, civil law, commercial law, criminal law, and trial law (both civil and criminal). It was written in an elegant, literary Spanish style, inspired by a theological vision of the world. It contains a Prologue, which lays out the object of the work, and seven parts, or books, called partidas, each of which starts with a letter of the name of the learned king, thus forming an acrostic of the name 'Alfonso': A seruicio de Dios... (For the service of God...) La ffe cathólica... (The Catholic faith...) Fizo Nuestro Sennor Dios... (Our Lord God did...) Onras sennaladas... (Special rites...) Nascen entre los ommmes... (Among men there