Etymologiae (Latin for "The Etymologies"), also known as the Origines ("Origins") and usually abbreviated Orig., is an etymological encyclopedia compiled by Isidore of Seville (c. 560–636) towards the end of his life. Isidore was encouraged to write the book by his friend Braulio, Bishop of Saragossa. "The Etymologies" summarized and organized a wealth of knowledge from hundreds of classical sources; three of its books are derived largely from Pliny the Elder's "Natural History". Isidore acknowledges Pliny, but not his other principal sources, namely Cassiodorus, Servius and Solinus. The work contains whatever Isidore, an influential Christian bishop, thought worth keeping. Its subject matter is extremely diverse, ranging from grammar and rhetoric to the earth and the cosmos, buildings, metals, war, ships, humans, animals, medicine, law, religions and the hierarchies of angels and saints.