Gilbert, physician to Queen Elisabeth I, attempted to map the world of the Moon with the unaided eye, even before the telescope of Galileo. In antiquity, Plutarch had surmised the existence of land and ocean regions in the dark and light patches of the lunar surface. Gilbert agreed, naming the darker areas the great continents of the east, west and center, with various islands floating in the bright surrounding ocean. Contemporary geographical terminology abounds: regio (continent), sinus (bay), insula (island). The island of Brittannia lies toward the right margin, further reflecting this association between lunar and terrestrial geography, as if the Moon were a new world. This book is the first printed edition of Gilbert’s posthumously published papers. Gilbert is best known for his experimental study of magnetism, which influenced both Kepler and Galileo and is on display in the New Physics gallery at Bizzell Memorial Library.