A master who had been cruel to his slaves might become a slave in his turn, and undergo the torments he had inflicted on others. He who has wielded authority may, in a new existence, be obliged to obey those who formerly bent to his will. Such an existence may be imposed upon him as an expiation if he have abused his power. But a good spirit may also choose an influential existence among the people of some lower race, in order to hasten their advancement; in that case, such a reincarnation is a mission.
Allan Kardec