"A Crystal Age" it is a novel written by William Henry Hudson, an Argentine-English author, ornithologist, and naturalist. The book was first published in 1887 and is considered one of the earliest examples of dystopian science fiction.

The story is framed as a narrative within a narrative. It begins with the protagonist, an unnamed narrator, discovering an ancient manuscript while exploring a cave. The manuscript tells the story of a man who, after getting lost in a remote region of South America, stumbles upon a hidden utopian society.

In this utopia, known as the Crystal Age, the inhabitants live in harmony with nature and each other. The society has achieved a state of perfect balance and enlightenment. The people are vegetarian, live without violence or conflict, and have advanced scientific and artistic achievements. The crystal of the title refers to the transparent material that constructs their buildings and symbolizes the clarity and purity of their way of life.

As the protagonist explores this utopian world, he contrasts it with the civilization he came from, which is portrayed as corrupt and decadent. The novel raises questions about the nature of progress, the consequences of industrialization, and the possibility of creating a utopian society.

"A Crystal Age" is a thought-provoking work that explores social and environmental themes, making it a significant contribution to early science fiction literature.