We may question whether any of them would have produced the same sequence of periods of history, if the actual facts of history had been to them a sealed book.

Indeed we may be sure that they were surreptitiously and subconsciously using experience as a guide, while they imagined that abstract principles were entirely responsible for their conclusions.

And this is equivalent to saying that their ideas of progressive movement were really derived from that idea of Progress which the French thinkers of the eighteenth century had attempted to base on experience.
The influence, direct and indirect, of these German philosophers reached far beyond the narrow circle of the bacchants or even the wandbearers of idealism.

They did much to establish the notion of progressive development as a category of thought, almost as familiar and indispensable as that of cause and effect.

They helped to diffuse the idea of "an increasing purpose" in history.