Treatise on calendars, a study of astrological calculations

beginning of 13th century

This work concerns the astrologically propitious moments for a whole variety of actions like journeys by land and sea, accession to the throne, waging war, treating illnesses, the education of children, trade, the transfer of property, the construction of buildings, taking purges and visiting the baths. Comprising 79 sheets of text, diagrams and illustrations, it is divided into two sections: “The Choice of Propitious Moments for All Kinds of Actions” and a “Book on the Reliable Way to Read Signs so as to Deduce Unspoken Thoughts”. Produced at the court of the last Abbasid caliph Al-Musta’sim (1213–1258) probably for one of his sons, as stated in the dedication, the manual bears witness to the close links between astrology and astronomy in the medieval period.