The Mystery of the Ancient Book of the Dead

Depictions on tomb paintings from the time period of the Third Dynasty of Egypt (between 2670-2613 BC) were sources of the text of the Book of the Dead, and they were written on papyrus, along with illustrations, in the tombs and graves alongside the dead. Instructions in the Book of the Dead also included instructions on how to take on the form of mythical creatures, as well as details of passwords to enable them to get through to the different stages of the underworld. In the time period before the New Kingdom of ancient Egypt, the Book of the Dead was something that was only available to the elite and royalty and the popularity of the Osiris myth during the period of the New Kingdom, meant that people thought that the spells were indispensable because of the fact that Osiris was featured constantly during the souls journey in the afterlife. Because the book eventually was in such demand by all peoples of ancient Egypt, book scribes then made them available to anyone and spells in the book could have been tailor made, according to the budget of the scribes’ customers.
It wasn't until 650 BC, when the Book of the Dead was fixed at a 190 spells per book, but it was common that people would add or remove certain spells as they saw fit but its seemed like the most common spell, was Spell 125, which was a spell which talks about the judging of the heart of the deceased by the god Osiris in the Hall of Truth. PICTUREIt was important the soul passed the test, in order to gain paradise and knowing what to say and act when being presented before Osiris, Thoth, Anubis and the 42 judges was the most important piece of information that the deceased would need to move through the paradise.
On the event of death, it is said that the soul was guided by Anubis to the Hall of Truth where a declaration of innocence would be made, also called the Negative Confession. Once this was made, gods Osiris, Thoth, Anubis and the 42 judges would confer and if the confession was one of acceptance, then the heart of the deceased was weighed against the white feather of Ma’at, which was referred to at the feather of truth and of the heart weighed in lighter than the feather, then this meant that the soul has passed the judgement and was allowed to go into paradise. But on the other side of the scale, if they heart was heavier than the feather, is was thrown onto the floor where goddess Ammit would eat it and the soul of the deceased would disappear.
Take a look at the Ancient Egyptian Book of the Dead yourself, available here.