A staff, then, like any other object, must have weight. Like any other object, the staff's weight is concentrated in its "center of gravity." Everyone, and everything, has a center of gravity. Depending on the object's shape, its center of gravity may be difficult to find; but an object's center of gravity is the point around which the object, if thrown, rotates. It is the point where an object can be balanced, even upon a very sharp point, as long as the point is placed directly under.
This brings us back to the staff. A staff, by definition, is a simple rod. It is, in essence, a three-dimensional line. Thus, a staff, as long as it is straight and true, must have its center of gravity directly in its middle. There, in its exact middle, lies the point around which it rotates, and there lies the point where it may be balanced.
Ok. A staff has mass, so it has weight. It has weight, so it rotates around its center of gravity. Its center of gravity has to be in its middle. So what?
So, this brings us to torque, both the key, and the "ki," (ha!) to the staff's power. Stay tuned...