 History, according to Hegel's metaphysical account, is driven by ideological development.  Ideological—and therefore historical—change occurs when a new idea is nurtured in the environment of the old one, and eventually overtakes it.  Thus development necessarily involves periods of conflict when the old and new ideas clash.  A second account of change is contained in the master-slave dialectic of Hegel's Phenomenology of Spirit (1807, 143–152; 192–198 ).  Certain forms of social hierarchy are intrinsically unstable.  The human desire for recognition drives social development, which consists of repeated struggles for recognition, until it reaches the liberal solution.  In the liberal state, slave and masters are abolished, and all recognize all as free and equal.  This arrangement lacks the contradictions inherent in previous social forms. 