This series is a survey of the Church's response to the challenge of the twentieth century. One hundred and fifty books by scholars of wide reputation, each, an expert in the field he describe, will cover the whole areaof modern knowledge in the light of Catholic teaching. Each volume, although a part of the overall encylopedic structure, is self-contained with its own list of references and bibliography. The series is grouped in sections and the covers of the books in each section are coloured uniformly for easy reference.