In Egyptian mythology, Ma'at (Ma) was the wife of Toth. Her name means "Truth", "Justice", and perhaps even "Tao". It cannot readily be rendered into English but "truth" is perhaps a satisfactory translation. Ma'at was represented as a tall woman with an ostrich feather in her hair. She was present at the judgement of the dead; her feather was balanced against the heart of the deceased to determine whether he had led a pure and honest life.
All civil laws in Egypt were held up to the "Law of Ma'at", which essentially was a series of old conceptions and morals dating to the earliest times in Egypt. A law contrary to the Law of Ma'at would not have been considered valid in Egypt.
SEE ALSO Toth.
[Source: Shawn C. Knight, "Egyptian Mythology FAQ" ]