Book excerpt: The 100 Most Influential Scientists is part of the Britannica Guide Series that offers a look into 100 scientists from Ancient Greece to the present day. The Britannica Guides series offers an essential introduction to many of the key issues of our time. Clear, accurate, and meticulously researched, the series gives both background and analysis for when you need to know for sure what is really happening in the world, whether you are an expert, student, or traveler.