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 is 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.