The most interesting unknown book I've read was Plato and the Creation of the Hebrew Bible by Russell E. Gmirkin. It'a an academic thesis and not really written for readability by the general public, but the ideas it presents are mind blowing. The gist is a theory that the Hebrew Bible was written by pre-Jewish scholars and politicians who studied Plato's works at the Library at Alexandria with the goal of uniting (12) disparate pre-Jewish tribes into one nation modeled after Plato's Republic. It's interesting both as a challenge to the mainstream theory that Plato's works were inspired by the Hebrew Bible, and as a look at an ancient social engineering project that still has huge implications thousands of years later. https://www.goodreads.com/book/show/32183185-plato-and-the-c...