Book excerpt: Somnium is a Latin word for Dream. This novel was written by Johannes Kepler in 1608, in a time when a trip to the ethereal regions of the moon would be possible only with the assistance of supernatural forces. Historians consider this lunar exploration a remarkable and revolutionary text, and one of the most provocative and innovative of Kepler's works. Great authors/scientists such as Isaac Asimov and Carl Sagan suggested it as the first science fiction story. If it is not, we can at least consider it as the first serious scientific work about lunar astronomy.