This book, written in elegant French by a mathematician and historian of mathematics J.-P. Pier, is a special and very interesting contribution to the history of mathematics, the history of science and science itself. The author asks some provocative, creative and motivational questions and he tries to answer them from many points of view (such as mathematics, philosophy, history and sociology). He describes what mathematics means for mathematicians and others and he shows the position of mathematics in our scientific system. He also deals with the influence of mathematics on the historical development of philosophical ideas, daily life, technology and culture, etc. He discusses why we like or dislike mathematics, why we divide mathematics into two parts: pure and applied mathematics or classical and modern mathematics, and how we apply and use mathematics in technological progress, our daily life and work. Each of his ideas is described and illustrated with perfectly chosen subjects or examples from number theory, algebra, geometry and analysis. To underline his ideas, the author gives many interesting quotations and sentences from the works of principal mathematicians, physicists and philosophers. The book is written like a remarkable and easily readable essay and can be recommended to all people who are interested in mathematics, the history of mathematics, philosophy and the history of science.