Any influence that can achieve its end falls within its definition. This includes moral appeals, the power base of priestly castes.
History is replete with priestly castes usurping and holding power by moral means.
And some of the profoundest rebellions in human history have been against moral power. There is no doubt that blacks have gained a moral victory over whites in the wake of the unspeakable violence that whites have perpetuated against them for hundreds of years. But no form of power is exempt from being abused. And in fact, blacks have used their moral advantage to stifle freedom of expression and freedom of conscience in the mixed race. The means by which blacks abuse their moral power is the one-drop rule.