Thus the racial history of Europe, which forms the author’s main outline and subject and which is wholly original in treatment, might be paraphrased as the heredity history of Europe. It is history as influenced by the hereditary impulses, predispositions and tendencies which, as highly distinctive racial traits, date back many thousands of years and were originally formed when man was still in the tribal state, long before the advent of civilization. In the author’s opening chapters these traits and tendencies are commented upon as they are observed to-day under the varying influences of migration and changes of social and physical environment. In the chapters relating to the racial history of Europe we enter a new and fascinating field of study, which I trust the author himself may some day expand into a longer story. There is no gainsaying that this is the correct scientific method of approaching the problem of the past. The moral tendency of the heredity interpretation of history is for our day and generation and is in strong accord with the true spirit of the modern eugenics movement in relation to patriotism, namely, the conservation and multiplication for our country of the best spiritual, moral, intellectual and physical forces of heredity; thus only will the integrity of our institutions be maintained in the future. These divine forces are more or less sporadically distributed in all races, some of them are found in what we call the lowest races, some are scattered widely throughout humanity, but they are certainly more widely and uniformly distributed in some races than in others. Thus conservation of that race which has given us the true spirit of Americanism is not a matter either of racial pride or of racial prejudice; it is a matter of love of country, of a true sentiment which is based upon knowledge and the lessons of history rather than upon the sentimentalism which is fostered by ignorance. If I were asked: What is the greatest danger which threatens the American republic to-day? I would certainly reply: The gradual dying out among our people of those hereditary traits through which the principles of our religious, political and social foundations were laid down and their insidious replacement by traits of less noble character. HENRY FAIRFIELD OSBORN. July 13, 1916. PREFACE TO SECOND EDITION History is repeating itself in America at the present time and incidentally is giving a convincing demonstration of the central thought in this volume, namely, that heredity and racial predisposition are stronger and more stable than environment and education.