Here's why you might be asking this question and some possibilities:
* Misunderstanding: Perhaps you've heard a story or myth about a secret book, but the details are unclear. It's important to remember that "secret" can mean many things: hidden, coded, confidential, or even just unknown to the general public.
* Specific Genre: You might be thinking of a book in a specific genre like mystery, thriller, or fantasy, where a secret book plays a pivotal role in the plot.
* Historical Context: 1872 was a significant year in history. It was a time of rapid change and social upheaval, so there might be historical texts with hidden meaning or secrets that are now considered obscure.
To help me give you a more specific answer, please tell me:
* What is the context of your question? Where did you hear about this "secret book"?
* What do you know about it? Do you have any details about its content, author, or purpose?
* What kind of secret are you looking for? Is it a hidden message, a lost piece of history, or a hidden treasure?
Once I have more information, I can help you find the answer you're looking for.