Power: the ability to produce results in general- or specifically, the ability to produce results with a relatively small amount of energy focused very precisely, especially after careful observation of where and how to add energy to produce a targeted result.
Observation and understanding are the root of power, not the total energy invested. Knowing where to add energy (or even where to remove energy) is crucial. Then, a focused application of a precise amount of energy can produce enormous results. Leverage is the ratio of the amount of effort invested to the size of the result produced.