I'll take liberty over power any day. But if you're talking of things such as military power, that is needed to maintain and proliferate liberty as well. You can have power without liberty, but it will be hard to maintain liberty without power. And that power is held not just by the government which would have armies to defend against foreign hostilities. But it must also include the people with the power to dispose of the government should it try to encroach too much upon liberty.