Heraclitus said that it is impossible for a man to step into the same river twice. It is impossible for two reasons: the second time it is not the same river and the second time it is not the same man. In the interval of time between the first and the second stepping, no matter how short, both the river and the man have changed. Neither remains the same. This is the central theme of the Heralictean philosophy — the reality of change, the impermanence of being, the inconsistency of everything but change itself. The Social Order, 1970 (3rd ed.), Robert Bierstedt, P. 509
Social change is the alternation in pattern of social structure, social institutions, and social behaviour over time.
Sociology, 1977, IAn Robertson, Worth Publishers, Inc. P. 539