With respect to the manner of presenting the selections, I have sought: (1) to offer careful translations--some made afresh from the printed originals, others adapted from good translations already available--but with as much simplification and modernization of language as close adherence to the sense will permit. Literal, or nearly literal, translations are obviously desirable for maturer students, but, because of the involved character of mediaeval writings, are rarely readable, and are as a rule positively repellent to the young mind; (2) to provide each selection, or group of selections, with an introductory explanation, containing the historical setting of the extract, with perhaps some comment on its general significance, and also a brief sketch of the writer, particularly when he is an authority of exceptional importance, as Einhard, Joinville, or Froissart; and (3) to supply, in foot-notes, somewhat detailed aid to the understanding of obscure allusions, omitted passages, and especially place names and technical terms. For permission to reprint various translations, occasionally verbatim but usually in adapted form, I am under obligation to the following: Messrs. Houghton, Mifflin and Co., publishers of Miss Henry's translation of Dante's _De Monarchia_; Messrs. Henry Holt and Co., publishers of Lee's _Source Book of English History_; Messrs. Ginn and Co., publishers of Robinson's _Readings in European History_; Messrs. Charles Scribner's Sons, publishers of Thatcher and McNeal's _Source Book for Mediaeval History_; Messrs. G. P. Putnam's Sons, publishers of Robinson and Rolfe's _Petrarch_; and Professor W. E. Lingelbach, of the University of Pennsylvania, representing the University of Pennsylvania _Translations and Reprints from the Original Sources of European History_. In the preparation of the book I have received invaluable assistance from numerous persons, among whom the following, at least, should be named: Professor Samuel B. Harding, of the University of Indiana, who read the entire work in manuscript and has followed its progress from the first with discerning criticism; Professor Charles H. Haskins, of Harvard University, who has read most of the proof-sheets, and whose scholarship and intimate acquaintance with the problems of history teaching have contributed a larger proportion of whatever merits the book possesses than I dare attempt to reckon up; and Professors Charles Gross and Ephraim Emerton, likewise of Harvard, whose instruction and counsel have helped me over many hard places. The final word must be reserved for my wife, who, as careful amanuensis, has shared the burden of a not altogether easy task. FREDERIC AUSTIN OGG. CAMBRIDGE, MASS. INTRODUCTION THE NATURE AND USE OF HISTORICAL SOURCES [Sidenote: The question of authority in a book of history]