When the People Fell — Cordwainer Smith

A sweeping saga of the centuries to come, from the new dark age that followed a global war, to the new civilization that arose from the ashes to colonize the stars. At first, the colonists use ships with gigantic sails, cruising on the waves of starlight, their captains having to become something part human and part machine; then later moving by planoforming ships which travel faster than light, but must defend themselves against the malevolent, mind-devouring creatures lurking in the dark between the stars. Then came the reign of the all-powerful Lords of the Instrumentality, who ruled Earth and its colony worlds with ruthless benevolence, suffocating the human spirit for millennia-until the time of the Rediscovery of Man, when the strange, lost concept of freedom was reborn. . . .