When the established order has become unsustainable and the abuse of power is oppressive and obvious to those around you, then you may act in unison to challenge that order and change it. You cannot do it alone. Such action requires moral authority, inner strength and allies in influential positions.
Any overt action will be met with strong resistance, so it is important to know its nature and find an opening that does not meet it head on, but rather subverts it from the inside. You need allies even within the opposition. First, find the obstruction and free it within yourself. Others can then be made aware of it and free it within themselves. Find unity within opposition.
