From the ancient days of the King Solomon to the modern times of Mark Twain’s romance The Prince and the Pauper, there were numerous legends and folk stories about entwined destinies of the people who shared the same date of birth. Many thinkers and astrologers have tried to explore this phenomenon, but there were no solid facts confirming these legends. Celestial Twins is the first evidence-based work that establishes the historical truth behind such myths, exploring 17 representative life stories. It begins as a tale of one curious observation of meaningful interconnectedness between life-paths of two historical personalities born on the same day of the same year. This accidental observation led to a systematic 15-year study of well-known celestial twins in which cases of such entwined life stories were detected and studied. This research led to the discovery of a new phenomenon—the Effect of Celestial Twins (ECT)—which demonstrates that though each human being is unique, there is fairly exact matching between the biographical data of celestial twins. All personages in these stories are well-known historical characters, such as Ernest Hemingway, Oscar Wilde, Nancy Astor, King George VI, Carl Gustav Jung, and Pablo Casals. Each of them was believed to have an unprecedented life path; and yet each person in these stories had a “twin” who had the same unique life task, used the same methods to complete it, and gained the same results.