For many years, I have been fascinated by the Mysterium Cosmographicum. I mentioned it in the first Sparlock novel.
Johannes Kepler thought he discovered God’s plan for the cosmos. Kepler suggested that the distances between the six planets known at the time could be represented by arranging the five Platonic solids within six spheres.
He could never get his model to fully agree with observation. However he eventually discovered three laws of planetary motion that do accurately describe the motions of the planets.
See also this Wikipedia article about the Mysterium Cosmographicum.