Take a gander at the Sith code real quick will ya?
Peace is a lie, there is only passion.
Through passion, I gain strength.
Through strength, I gain power.
Through power, I gain victory.
Through victory, my chains are broken.
The Force shall free me.
This says nothing about rage, anger, fear or anything of that nature really. This seems to me more like a creed, declaration, whathaveyou of someone who refuses to be enslaved. This could mean by the jedi, by their emotions, whatever, but you get my point.