The modern name given to a collection of ancient Egyptian mortuary texts made up of spells or magic formulas, placed in tombs and believed to protect and aid the deceased in the hereafter. The collection, literally titled The Chapters of Coming-Forth-by-Day received its present name from Karl Richard Lepsius, German Egyptologist who published the first collection of the texts in 1842. It was probably compiled and re-edited during the 16th century BC, and over half of the collection is comprised of the Coffin Texts dating from c 2000 BC and the Pyramid Texts dating from c 2400 BC. The Book of the Dead had numerous authors, compilers, and sources. Scribes copied the texts on rolls of papyrus, often with illustrations, and sold them to individuals for use in burials. Many copies of the book have been found in Egyptian tombs, but none contains all of the approximately 200 chapters. The choice of spells varies from copy to copy.