George White's Ornithopter, 1928
Every few hundred years in Western history there occurs a sharp transformation. Within a few short decades, society - its world view, its basic values, its social and political structures, its arts, its key institutions - rearranges itself. And the people born then cannot even imagine a world in which their grandparents lived and into which their own parents were born. We are currently living through such a transformation. - Peter Drucker