"A collection of works by Herbert Spencer, one of the greatest philosophers of the 19th century, which includes his key works in sociology, philosophy of science, and political economy. In this collection, you will find works that have become classics in their fields, such as Principles of Sociology, Primary principles" and "Principles of psychology". Readers will have the opportunity to delve into the thoughts of an outstanding philosopher and scientist who made a significant contribution to the development of scientific disciplines." (Book title: "The Collected Works of Herbert Spencer")