Ma’at’s feather is used as the weight in the ancient Egyptian judgment of the dead.
In the weighing-of-the-heart scene, the deceased’s heart is placed on one side of a balance and Ma’at’s feather on the other. Ma’at represented truth, justice, balance, order, and proper cosmic harmony. A heart that balanced with the feather indicated that the deceased was fit to enter the blessed afterlife.
The feather is generally shown as an ostrich feather and also functions as a recognizable emblem of the goddess. The scene appears prominently in Book of the Dead illustrations, especially those associated with Spell 125. Anubis commonly supervises the scales, while Thoth records the outcome and Osiris presides over the judgment.
The heart was especially important in Egyptian ideas of personhood and morality. Unlike the brain, it was often left in the body during mummification because it was regarded as the seat of thought, memory, character, and moral identity. A failed judgment could lead to Ammit devouring the heart.