One of the roles of Anubis was as the "Guardian of the Scales."[41] The critical scene depicting the weighing of the heart, in the Book of the Dead, shows Anubis performing a measurement that determined whether the person was worthy of entering the realm of the dead (the underworld, known as Duat). By weighing the heart of a deceased person against Ma'at (or "truth"), who was often represented as an ostrich feather, Anubis dictated the fate of souls. Souls heavier than a feather would be devoured by Ammit, and souls lighter than a feather would ascend to a heavenly existence.[42][43]