It is something the rational mind cannot comprehend without bending to the mind of feeling. Cause and effect must content themselves with filtering through irrational humanity.
To think of history as a process of human action is to imagine a long chain of mistakes and accidents leading forth to join in the present day and splaying their long threads again out into the future. We live in an aggregating comb that for one brief moments scoops these threads together and slides along with the progression of time. The loom of fate is threaded with mistake and mishap.
And it is right here that we find a driving force. In the friction between the reality as it is to the mind, and the reality as it must be. Rather, humanity builds for itself insane paradigms of thinking that it believes in with all faith: building reality out of nothing but sand and salt. But as long as there is disagreement, what is real must be. Be it now or be it a thousand years hence. As long as there are eyes that see a second view.
The fiction-makers will perpetrate their fictions until their failure becomes obvious. A new fiction adapted to those failings rises in its place and carries on until it suffers the same fate. This continues until oblivion. The real continually runs away from these fictions, changing and shifting and slipping behind corners. It is never caught.
Yet driving all on and on is the continual adaptation of fiction as it chases reality. We can only live in fiction; yet glimpses of the real make us break the fiction again and again. And in this fight is the driving force of all of human life.