"Letters from Earth" is a science fiction novel written by the American writer Robert Heinlein. In this book, the author talks about the changed Earth society, which has undergone revolutionary transformations under the influence of aliens from another planet. The main character finds himself in this new world, where completely different laws and values rule. Through the prism of an adventure plot, the author reveals deep philosophical and social problems, prompting the reader to think about the nature of man, his place in the universe and possible ways of development of civilization. "Letters from Earth" is not only fascinating science fiction, but also a wise reflection on the future of humanity and possible ways of its self-realization.