Through Nature to God is a Religious Book. The book says that Single purpose runs throughout this little book, though different aspects of it are treated in the three several parts. The first part", The Mystery of Evil", written soon after "The Idea of God", was designed to supply some considerations which for the sake of conciseness had been omitted from that book. Its close kinship with the second part",The Cosmic Roots of Love and Self-Sacrifice", will be at once apparent to the reader.