Time of Variables is a fun book about mathematics all around us. Twenty-eight fascinating stories devoted to various aspects of mathematics are accompanied by amusing author's drawings. Mathematical analysis for Orlin is a universal language that can express everything that we face every day - love, risk, time, and, most importantly, constant change. The theme of the movement of time is reflected in the titles of parts of the book - "Moments" and "Eternity", and in its characters - from Sherlock Holmes to Mark Twain and David Foster Wallace. With his characteristic humor and ingenuity, Orlin makes connections between calculus, art, literature, and his beloved dog, Elvis. The author of the sensational "Mathematics with Stupid Drawings" in this book, too, aims not only to captivate the reader with his favorite subject, but to make us wiser and more thoughtful.