If it be true that a book well recommended by competent critics is sure of a hearty welcome from thoughtful readers, the present volume will find favor with the Catholic public. During the fifteen years of its existence the French original has passed through twelve editions. It has been praised by the Catholic press and has received a flattering recognition on the part of cardinals and prelates. Thus Cardinal Mazzella wrote to the author: " You unite with soundness of doctrine the clearness of exposition which the intelligence of the pupil requires, and you treat your subjects with the reserve necessary to permit the professor to add his own developments. I hope that your work will become a classic textbook to the great advantage of students. People of the world will also read it with profit and pleasure."