Ma'at — whose name means "that which is straight," "truth," "justice" and "order" simultaneously — is the Egyptian personification of the fundamental order of the universe. She is depicted as a woman with an ostrich feather on her head — or sometimes as the feather itself — seated or standing in a posture of perfect composure. She is the daughter of Ra (the sun god) and the wife of Thoth (the god of wisdom and justice), making her the child of cosmic creative power and the partner of cosmic intelligence.
Ma'at is not simply the goddess of truth in the way that, say, Athena is the goddess of wisdom. She is something more fundamental: the right order of existence itself. She is the principle that the sun rises each morning, that the Nile floods each year, that the seasons follow each other in sequence, that the stars maintain their positions. She is the principle that kings govern justly, that contracts are honoured, that the weak are protected from the strong. She is the principle that makes the universe a cosmos rather than a chaos — the intelligence embedded in the structure of things.
Her opposite is Isfet — chaos, injustice, disorder, falsehood. The entire project of Egyptian civilisation was understood as the maintenance of Ma'at against the constant threat of Isfet. The pharaoh's primary religious duty was to "uphold Ma'at" — to maintain the conditions of cosmic order in the human realm as Ra maintained them in the cosmic realm. Every morning, the pharaoh performed rituals that symbolically renewed Ma'at; every just act of governance was an enactment of Ma'at; every temple, every canal, every harvest was Ma'at made manifest.
She was present at the creation of the world — Ra created the cosmos by speaking Ma'at into existence. She is simultaneously the product of creation and its condition: the universe was created in accordance with Ma'at, and Ma'at is what the universe requires to continue. Without her, the sun would not rise, the Nile would not flood, and the cosmos would dissolve back into the primordial chaos from which it came.