When people talk about "history," their subconscious often conjures the image of a "long river." For most, the abstract concept of history is just an ever-accumulating pile of old papers and a metaphorical river that flows forward.
Historians describe it more accurately and appositely, presenting history as a spiraling staircase ascending step by step. People always witness many familiar things replaying, while at the same time, society is indeed making constant progress.
Perhaps this is true.
But people should not forget that everything has two sides, and Newton's third law of classical mechanics also states that for every action, there is an equal and opposite reaction. If there are forces that propel history forward, there must also be forces that wish to turn back the clock and bind the world in the old ruts of the past—that is, the so-called "reactionary" forces.
