Complex sentence: At the time, the Sun, Moon and planets were thought to revolve around the earth in their proper spheres-the most thorough and imaginative description of the concept can be found in Dante's "Divine Comedy".
Split into simpler sentences: At the time, the Sun, Moon and planets were thought to revolve around the earth in their proper spheres. The most thorough and imaginative description of the concept can be found in Dante's "Divine Comedy".