In most courtrooms built in the colonial period, we see the image of a woman with a blindfold balancing scales in her arms. This is Lady Justice based on a Greek goddess described in Hesiod’s Theogony called Dike, daughter of Zeus, who is associated with human while her mother Themis is associated with divine justice. In art, she was shown bearing scales. Her Roman form, Justitia, was blindfolded. She was imagined as innocent looking, throttling the ugly Adikia (injustice) and beating her with a stick, or killing her with a sword. The story goes that she lived with humans in the Golden and Silver Age, when there were no wars. But then humans grew greedy and justice was forgotten and Dike ran away to be with her father, high on Mount Olympus, away from human corruption.
The idea of associating justice with scales is much older though and can be traced to the Egyptian Goddess of justice, Maat, and later Isis. The feather of Maat was used to weigh the heart of the dead, to see if they were worthy of entering the land of Osiris, or if a monster should simply eat them, depriving them of the afterlife. The idea spread from Egyptian mythology through Greek mythology to Christian mythology with the Archangel Michael often shown holding scales. Sin makes the heart heavy, and causes the sinner to be cast in Hell. The virtuous go to heaven.