In search of means to revive in wide circles interest in mathematics, I came up with the idea to collect a number of works that treat mathematical topics in a fiction or semi-fictional form, and offer them to the reader with relevant comments. The number of such works is, of course, very limited. This explains the modest size of the present collection. However, the mathematical topics covered in it are still quite diverse: relativity of space and time, four-dimensional world, calculations from the field of celestial mechanics, questions of mathematical geography, combinatorics and giant numbers, application of mathematical analysis to games, indefinite analysis, equations. It is hoped that this small collection will lead other readers to more serious reflection and will encourage systematic acquaintance with a particular department of mathematics. This collection is the first known experience of this kind ..