Kingdom of Ends

A good will is not a means to an end.  It is an end in itself.  Humans, insofar as we are defined by our good will (good practical reason), are also ends in ourselves.  A human is not to be used as a means to an end.  Kant imagines a kingdom of ends, where humans agree to abide by common law.  Because each person can legislate universal law by using his or her practical reason, each person is able to hold power over herself and others in a mutually consenting manner.  This power to legislate universal morality is what Kant calls the autonomy of the will.