Sorrow of the Earthmother is a part of tauren mythology. It is recorded in-game on a wall hanging in the Archdruid's tent in Thunder Bluff.
As the children of the earth roamed the fields of dawn, they harkened to dark whispers from deep beneath the world. The whispers told the children of the arts of war and deceit. Many of the Shu'halo fell under the shadow's sway and embraced the ways of malice and wickedness. They turned upon their pure brethren and left their innocence to drift upon the plains.
The Earthmother, her heart heavy with her children's plight, could not bear to watch them fall from grace. In her grief, she tore out her eyes and set them spinning accross the endless, starry skies. An'she and Mu'sha, seeking to ease the other's sorrow, could only chase each other's faint glow across the sky. The twins still chase one another with every turning of the world.
Though sightless, the Earthmother could not long stray from the world of her heart. She kept her ear to the winds and listened to all that transpired across the fields of the dawn. Her great heart was always with her children - and her loving wisdom never fled from them.