This book is one of the five basic works that make up the Codification of Spiritism, and is the author’s most scientific work. It deals with themes regarded as incontestable by religion in the light of the immortality of the soul, unifying Christian thought and scientific discoveries. It offers a unique opportunity for the reader to know and study themes of universal interest, discussed in a logical, rational and revealing manner. It is divided into three parts: The first part analyses the origin of planet Earth and avoids mysterious or magical interpretations about its creation. The second part analyses the question of miracles, explaining the nature of the fluids and the extraordinary phenomena contained in the Gospel. The third part focuses on the prophecies in the Gospel, the signs of the times and the new generation, whose advent will be the beginning of a new era for humankind based on the practice of justice, peace and fraternity. The subjects presented in its eighteen chapters have as their basis the immutability of the grand Divine Laws.