Taken from the Star Wars Wiki:  

The Father was a powerful Force wielder who resided in the realm of Mortis. His children, the Daughter and the Son, represented the light side and the dark side of the Force, respectively. Balance was maintained between them by the Father until his failing health compelled him to search for a successor. 

During the Clone Wars, the Father guided Anakin Skywalker to Mortis in order to test the Jedi Knight's abilities and concluded that he was indeed the Chosen One destined to bring balance to the Force. Skywalker declined the Father's invitation to remain on Mortis, however. Moreover, the machinations of the Son ultimately resulted in the destruction of both himself and his family. Near death, the Father divined that one day Skywalker would fulfill his destiny.