"The Rediscovery of Man" is a collection of short stories (all set in the same universe at different time periods) by Cortwainer Smith. This universe is largely ordered by the Instrumentality, a governing body spanning centuries and controlling in fine detail the lives of almost every living human.
Like Huxley before him, Smith imagines a world in which genetics and behavioral conditioning sanitize life to the point where individual achievement is nearly meaningless. Smith's Instrumentality extends the control of science over nature somewhat further than Huxley, to the point where everyone is allocated 400 years of life (instead of the roughly 80 years of youth the denizens of Huxley's "Brave New World" lived). They live without fear of disease, weather, aging, hunger or the lack of material goods. Access to history is tightly controlled, and all divisions of language and culture have been more or less erased. At the height of the Instrumentality, the only human individuals not perfectly adjusted to the needs of their society and their own ability to fulfill those needs are extreme aberrations (and extremely rare).
The title "The Rediscovery of Man" refers to the reemergence of chance and diversity as means of allowing the human race continued growth. This relaxation of some of the controls on their society arises in no small part from the study of undermen, animals modified to resemble, interact with, and serve humans. Early in the timeline of the Instrumentality, undermen are slaves, less than human, destroyed when they fail or become inconvenient. They are utterly disposable labor, and only those who are strong, witty, and lucky survive. Thus it is that the various species of underpeople grow while the human race in its perfect control over heredity and environment stagnates.
The reemergence of human progress and the rise of the underpeople are two of the major themes. Minor themes include telepathy, the mob mentality and the progress of societies and technologies over millenia. Like Tolkien's Middle Earth, you get the sense that Smith had a full vision of this universe stretching over millenia, and that each story was just a window into a fully-realized world.
This is a great collection of stories, well worth reading and rereading. I look forward to reading the small collection of additional fiction works by the author.