Since his youth, the distinguished writer Fouad Sarrouf has been fascinated by biographies of great figures. He has read their biographies and perused pages from their lives. These biographies left an impact on him, which, after study, experience, and continued reading, transformed into a belief that the best means of presenting knowledge to young men and women and encouraging them to learn more of it is based on integrating various scientific facts into biographies of great figures, as they contain incidents and anecdotes that call for contemplation and reflection. The reader can also absorb them without much effort. This belief motivated the writer to take care to publish some of these translations in this book, which is divided into four chapters. The first chapter includes a group of the greatest modern astronomers, namely Copernicus, Kepler, Galileo, Newton, Herschel, and Einstein. The second chapter includes a group of the most famous discoverers in the field of physics and chemistry, namely Priestley, Lavoisier, Davy, Heller, Faraday, Maxwell, Michelson, and Langmuir. The third chapter deals with the most important researchers in the atom and its structure, namely Delton, Avogadro, Mendeleev, Curie, Kempson, Moseley, and Rutherford.