The main feature of the judgement of the dead when the heart of the deceased, regarded by Egyptians as the seat of intelligence, was weighed on a balance against the feather of maat, representing truth and righteousness. A virtuous heart would balance and admit the deceased to the afterlife, while a heavy heart would indicate an evildoer whose heart would then be devoured by a monster and hence denied an afterlife. The Book of the Deadwas designed to fix the balance with magic spells to enable the deceased to enter the afterlife without difficulty. Aheart scarab was often placed over the heart of the deceased with the same intention.
See also Religion.
Historical Dictionary Of Ancient Egypt by Morris L. Bierbrier
Ancient Egypt. A Reference Guide. EdwART. 2011.