The 12 called and empowered are the 12 faculties of a complete person, and the number 12 is the full circle of the developed self, the whole zodiac of powers arranged around a center and awakened together. To be given authority over unclean spirits is for each faculty to receive command over the disordered energies and impure states that trouble the inner life, so the powers that were passive become active governors. Casting out and healing are the ordering of the body-temple from within, the restoration of every function to its clean working.
The center of this is a self coming into its own rule. When the governing consciousness gathers its 12 powers and endows them, sickness and disorder inside a person yield, because the disciplined faculties now hold sway over the very disturbances that once ruled them.
The 12 disciples: the number 12, the complete circle of a person's faculties, the whole set of inner powers arranged around the center and awakened
Unclean spirits: the disordered, impure energies and states that trouble the inner life until the awakened faculties gain command over them