Power is immutable, it shifts from pony to pony, but power always goes somewhere, it does not vanish.

If there is one thing I have learned In all my years, it is that power is the most dangerous thing in existence. Specifically, the power beliefs, ideas; they make ponies commit the most heinous of crimes, believing they are doing the right thing.

It can also make way for the best of things, if wielded subtly. A subtle hint here, a gentle nudge there and one can even do something as seemingly impossible as break a banishment spanning a thousand years.