he Book of the Dead is made up of a number of individual texts and their accompanying illustrations. Most sub-texts begin with the word ro, which can mean mouth, speech, a chapter of a book, spell, utterance, or incantation. This ambiguity reflects the similarity in Egyptian thought between ritual speech and magical power. In the context of the Book of the Dead, it is typically translated as either "chapter" or "spell". In this article, the word "spell" is used.
At present, some 192 spells are known, though no single manuscript contains them all. They served a range of purposes. Some are intended to give the deceased mystical knowledge in the afterlife, or perhaps to identify them with the gods: for instance, Spell 17, an obscure and lengthy description of the god Atum.
Others are incantations to ensure the different elements of the dead person's being were preserved and reunited, and to give the deceased control over the world around him. Still others protect the deceased from various hostile forces, or guide him through the underworld past various obstacles. Famously, two spells also deal with the judgement of the deceased in the Weighing of the Heart ritual.