This third edition is published under the patronage of Georgetown University as a slight token of appreciation for the degree of Doctor of Letters, conferred on the author for this work at the last Commencement. This issue has been enlarged by the addition of many illustrations selected to bring out the fact that all the various parts of Europe shared in the achievements of the time and by an appendix containing in compendium Twenty-Six Chapters that Might Have Been. Each of these brief sketches could easily have been extended to the average length of the original chapters. It was impossible to use all the material that was gathered. These hints of further sources are now appended so as to afford suggestions for study to those who may care to follow up the idea of the Thirteenth as The Greatest of Centuries, that is, of that period in human existence when man's thoughts on all the important human interests were profoundly valuable for future generations and their accomplishments models for all the after time. {x} PREFACE. (FOURTH EDITION). Many of the now rather numerous readers and hearers of this book, for it has been read in the refectories of over 200 religious communities, have said that the title seemed almost deterring at first because of the high claim that is set up for a medieval century. To mitigate the possible initial deterrent effect of the paradox of the Thirteenth as the Greatest of Centuries, it has seemed worth while in this edition then to premise a series of quotations from some of the most distinguished historical writers in English of our own time which amply justify the claim here set up. Frederic Harrison, Macaulay, Freeman, and Fiske are sufficiently different in themselves to make their agreement in supreme admiration for the Thirteenth Century very striking. In spite of their lack of sympathy with many things in the period, all of them emphatically declare that it is the source of most that is great and good since, and that while we have added details, we have failed to surpass its artistic and intellectual achievement in all the 700 years that have elapsed. August 15, 1912. PREFACE. (FIFTH EDITION).