The book contains speeches by Academician P. L. Kapitsa to a wide audience, which contain a simple and clear presentation of his experimental research. The well-known essays on the life and work of outstanding scientists provide an analysis of their scientific creativity, revealing the objective reasons and individual traits that contributed to the success of their scientific work. The book also includes articles and speeches devoted to the organization of science, strengthening its connection with practice, creative education of youth, problems of relations between man and nature, the struggle for peace and progress. The book is intended for a wide range of readers interested in the ways of development of science.