"The Abolition of Man" remains one of Lewis's most prophetic works as social relativism has been uncritically adopted by modern thought--in religion, education, and government--opening the door to the post-modern claim that people are free to create their own reality through a sheer act of the will.
From the back:
In The Abolition of Man, C. S. Lewis sets out to persuade his audience of the importance and relevance of universal values such as courage and honor in contemporary society. Both astonishing and prophetic, this book is one of the most debated of Lewis's extraordinary works. National Review chose it as number seven on their "100 Best Nonfiction Books of the Twentieth Century."