British scientist Arthur Eddington was once more famous than Albert Einstein! Informed scientists understand how intertwined the two are. Einstein's theories are well known, but it was Eddington who proved and endorsed many of them. This book describes the rise of these two men and how their friendship fostered scientific breakthroughs and ultimately Einstein's fame. Readers will be interested in the accessible explanations of some famous theories, such as the Theory of Relativity, while the relevant photographs and fact boxes further clarify biographical details.