The Natural History of Unicorns by Chris Lavers
Unicorns, History, Mythology, Religion
Lavers takes you on a journey from ancient scholars who heard stories of Tibetan antelopes and turned them into unicorns, to Christians who turned other bi-horned quadrupeds into unicorns through a translation error, to ancient traders who turned narwhals into unicorns, and basically guides you through the history of the myth and all of the strange points it has reached along the way. I love this because he takes a fictional creature and treats it in a scholarly way, presenting various arguments and showing with pictures why people were so ready to believe in a creature they had never seen. He covers all of bases with humor, and the book is interesting from start to finish.