This book is devoted to Pyotr Nikolayevich Lebedev, a remarkable Russian scientist who lived and worked in the late 19th and early 20th century. The story of Lebedev's life is a striking and instructive example of selfless devotion to science. His name is associated not only with discoveries in the field of physics; he is known as the founder and head of the first major school of Russian physicists, which played a noteworthy part in advancing science in this country. Lebedev also founded Russia's first big research laboratory, where many prominent physicists were trained. Lebedev died in his prime, at the age of 46. The extremely trying conditions under which he had to work, accounted for his early death more than anything else. They prevented him from carrying out his far-reaching plans of scientific research and education in Russia. In this book an attempt is made to describe in popular form the essence of Lebedev's discoveries and to tell about his principal scientific works. At the same time the book deals with the main aspects of the short but colourful life and work of this remarkable man. Contents: Introduction -- Business or Science? -- Abroad -- Choosing a Road in Science -- Doctor of Science -- Riddle of the Comets -- Back in Moscow -- Action of Waves on Resonators -- Studying the Properties of Electromagnetic Waves -- Pressure of Light on Solid Bodies -- Establishing a School -- Pressure of Light on Gases -- Lebedev as a Pedagogue -- A New Plan -- Magnetometric Study of Rotating Bodies -- The Last Years -- Conclusion