The book "Philosophical Letters: or, Modest Reflections on Some Views in Natural Philosophy" is one of the most remarkable works of the author Margaret Cavendish, Duchess of Newcastle. In this work, she leads a discussion on philosophical issues, including belief in fate, natural law, the role of sensory perception, and other topics. Cavendish expresses his reflections on the nature of the world and man's place in it, based on his own unique view of philosophy. Marked by deep analysis and a high level of argumentation, this book offers the reader an opportunity to deepen his knowledge in the field of philosophy and to think about the eternal questions of existence.