From his observations of the vegetation of Nebraska and the western United States, Clements developed one of the most influential theories of vegetation development. Vegetation composition does not represent a permanent condition but gradually changes with time. Clements suggested that the development of vegetation can be understood as a unidirectional sequence of stages resembling the development of an individual organism. After a complete or partial disturbance, vegetation grows back (under ideal conditions) towards a stable "climax state", which describes the vegetation best suited to the local conditions. Though any actual instance of vegetation might follow the ideal sequence towards stability, it can be interpreted in relation to that sequence, as a deviation from it due to non-ideal conditions.