Now, the Force is a balance. Like the Chinese concept of Ying and Yang, the Light and Dark exist in an eternal cycle, a self-correcting transition from Shadow to Light, and back again.

Darkness has always had its part to play. Without it, how would we know when we walked in the light? It’s only when its ambitions become too grandiose that it must be opposed, disciplined, sometimes–if necessary–brought down for a time. Then it will rise again, as it must.

The Dark Side embodies such concept as anger, passion, strength, destruction, sorrow, chaos, power. Wild, untamed, and chaotic, it is not for the weak willed. It is dangerous, but by no means evil. Such power rewards the wise, and consumes the unwary.

The Light also has its place. It embodies caring, compassion, humility, charity, duty, healing, creation, and passivity. While it does not carry the risks of the Dark Side, it is also less eager to bend itself to the will of its ‘wielder’.
Now, seeing the benefits of both, you may ask ‘why not be a grey Jedi, and wield both?’

A house divided, as Jedi philosopher  Yahsuhowa Ben Yosef once said, cannot stand. You cannot pledge yourself to both the light and the darkness. To do so is to constantly switch between two incompatible extremes. Any who does so is a fool, a madman, or hopelessly conflicted.

Perhaps light and dark are poor names for the sides of the force. Perhaps the Passive Side and the Active, for the Light and Dark embody these concepts to some extent. Or perhaps the Serene and Passionate, for they also encompass that. The Creative and Destructive, Ying and Yang, Positive and Negative.

Light and Dark are just handles.

And Grey Jedi is a misnomer. The Force does not blend into one seamless whole mearly by wishing it. It is two forces acting as one. A Grey Jedi would be torn by the conflict between the sides.

Now, as the Force is derived from life itself, it depends to some extent on the actions of the living to maintain this balance. This balance is at times steady, and at times leans towards one side or another.

Some times, the Force seems to be stuck.  One side or the other may gain dominion over the galaxy. In such times, a hero (or villain) arises to bring balance to the Force.

Such a one was Anakin Skywalker when he slaughtered the Jedi order, correcting the mistake that Bane made, when forcing the Sith underground, yielding domino to the Jedi. Such a one was his son, when he restored the Jedi, as Sidious threatened to develop a stranglehold on the galaxy, just as did the Jedi.

Such a one was Ruin, when he encited the Fourth Great Schism. Such a one was Revan. These people, Jedi and Sith bother, are the true Champions of the Force, for it is they who restore the balance that is the core of the Force.

Now the pendulum swings freely between the Light and the Dark side, the Force is in balance once again.