Surely, the Libra has something to do with the goddess of justice in western world.

The origin of the myth is that the goddess of justice took scales and took charge of the duty of a judge to decide good and evil in the world of mortals. In the end that gods in world, the desires of human beings rose and the quarrels happened all the time. The goddess of justice leaned to the side of evil to get the balance. Other gods were angry and went back to the heaven. To protect human being not falling into the edge of sins, the kind goddess stilled stayed in the world and used the scales to judge the sin and persuade human beings following the standard of morality. Yet human beings did not listen to her words. Therefore the goddess of justice returned to the heaven after assuring the quarrel not to cease, and she made her scales becoming the constellation in the sky.

In the story, the meaning of goddess that astrologists explained is that the scale of judging good or bad, the kindness of the goddess and the process of abandoning human beings. In all the constellations, the Libra was the one which can judge the right and wrong of people mostly. Yet her kindness caused hypocrisy and resulted that she was the last one who left human beings (after assuring that there was no hope in the world).