However, consider the facts: Kepler lived in a world that was vary poised to the subject of science. Though it was coming into use at a rapid rate, it was still viewed as blasphemy by the church. His mother was accused of Witchcraft and, despite being imprisoned, was released for the "crime". It could be argued that it was easier for people to believe in Witchcraft than they did in scientific research. What better way to hide your theories in a book designed for fantasy? I think Kepler does this so, if he was ever caught, he can claim that the story is nothing more than a piece of fiction and meant to be taken as such.