Eager to preserve the Spanish and Arabic heritage, Miguel Casiri set out to catalogue the 1800 Arabic manuscripts in the Royal Monastery of San Lorenzo El Real, known generally by the title El Escorial. The resulting work was a monument of scholarship in the eighteenth century. Containing a number of quotes from Arabic sources on history, geographical and historical manuscripts, full text of both volumes, indicies, and subject divisions, this edition, part of Gorgias Historical Catalogues, serves as a historic and linguistic study, as well as a reference work.