WIST

It is impossible to divide the past into distinct, clearly defined periods and prove that one age ended and another began in a particular year, such as 476, or 1453, or 1789. Men do not and cannot change their habits and ways of doing things all at once, no matter what happens.

James Harvey Robinson (1863-1936) American historian and educator
An Introduction to the History of Western Europe, ch. 1 “The Historical Point of View” (1902)
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