I have shown that the relations of social structure to social action must be seen as a process occurring over time, with the reproduction and transformation of social structure understood as a process of temporal change. Social systems, therefore, are characterised by continual social change, sometimes small-scale and transient and sometimes large-scale and enduring. Where change is enduring and exhibits a direction, it is usual to speak of development rather than merely of change. Change and development are temporal processes, as discussed in Chapter 5, and the history of any social situation or social system requires a description and explanation of their changing patterns over time.