The book "Letters to Eugenia; or, A Remedy against Religious Prejudice" was written by the French philosopher Paul-Henri Thiry, Baron Dolna Holbach. In this work, the author reveals his rationalist views on religion and morality, refuting religious dogmas and exposing their contradictions. The book is an incendiary call for free thinking and analysis, aimed at keeping away from religious ideas that limit the development of a rational worldview. Because of its deep argumentation and strong advocacy of rationalism, "Letters to Eugenia" remain relevant even today, provoking discussions about faith, morality and the role of religion in society.