One of my best used-book finds ever was a copy of 1912's Hygiene for the Worker, a book published to help young men and women become happy, healthy, and unquestioning factory-laborers. The book is wonderful in so many ways. The illustrations are simultaneously delightful and creepy, the language is charmingly outdated, and the lessons in the book attempt to create a race of scrubbed-clean, milk-drinking super employees who spend their vacations at home "laying up a greater store of health and energy than the young people who come back tired and weary from having too good a time at the mountains and other regular summer resorts."
I love Hygiene for the Worker a lot, and thus I was pleased to recently discover that it has been digitized by Google Books. I highly recommend taking a skim through this hilariously outdated, yet sometimes disturbingly pertinent book.