Hypatia of Alexandria was one of the first women philosophers and, nevertheless, the history books have not been very fair to her. A great Neoplatonic teacher, Hypatia excelled in the fields of astronomy and mathematics, although she is also remembered as a brilliant inventor: she improved the astrolabe (a very useful navigation tool, based on the position of the stars) and developed the first device that could measure the density of liquids. This book tells the story of how she managed to do so much in a world dominated by men, and the story is exciting.