PREFACE 



IT IS a large task to select out of the world's knowledge all that is most interesting, 

 illuminating and useful, and present it in an orderly manner so that it can be com- 

 prehended, enjoyed and utilized alike by young and old. I feel that this task has 

 been well accomplished in THE WORLD BOOK. My confidence in the value and service- 

 ableness of these volumes steadily increased as the work of preparation pro- 

 gressed. No one could observe without admiration and enthusiasm the building of 

 Tin: WORLD BOOK, which has required the organization and attractive presentation 

 in story and picture of the important truths in every department of human interest, 

 achievement and investigation. Many minds and hands, and I think I may say 

 many hearts also, have cooperated in the making of these books, and each has done 



-I>ecial work faithfully and enthusiastically, because he has felt the spirit and pur- 

 pose behind THE WORLD BOOK, so to present all important knowledge that it will 

 make a strong appeal to every normal person and become a comfort and guide to him 

 in his daily life. 



Men and women of these times have the same sort of problems that people had 

 centuries ago. But earlier peoples had to solve their problems largely by trial and 

 error. They did not have access to the wisdom of the past as a guide for the present. 

 People to-day, though, may profit by all the experiences of those who have gone before 

 us, and in THE WORLD BOOK these experiences are described and their outcome por- 

 trayed. Particular attention has been given to modern developments in the sciences 

 that deal with human welfare, and with human nature in its physical, mental, social, 

 economic, political, ethical and moral aspects. The stories are told in a simple, 

 straightforward way, the purpose being to make all truth of whatever sort intelligible 

 and attractive. 



It is more important to-day than it ever has been to conserve the time and energy 

 of young people in school. Knowledge is accumulating rapidly; there is much more 

 to learn now than there was a few decades ago. Upon teachers and parents rests 

 the responsibility of guiding the young so that they will master all really vital knowl- 

 edge readily and without waste. In the preparation of THE WORLD BOOK the needs 

 of those who instruct youth have been kept constantly in view. Every subject of 

 irist ruction in the elementary and high schools is discussed herein. The story of each 

 branch is presented in the proper place, and it is shown how it has been developed, 

 what role it plays in human life, what its value in modern education is, and how each 

 topic can best be presented so as to enlist the interest of the learner, and so that it 

 will remain with him and be assimilated into his thought and conduct. 



For the benefit of parents, teachers, and all who would keep in touch with the 

 development of education there are articles on many special subjects, such as the 

 measurement of t he intelligence of children, the use of standards and scales in determin- 

 ing progress in educational work, the use of museums as an aid in making teaching 

 concrete, the development of cooperative work among teachers and parents, the ex- 

 tension of the principles of the Montessori system to general education, the principles 

 underlying the Gary educational system, and so on. 



As a rule encyclopedias are apt to be quit, formal and technical. A faithful effort 

 has been made i n Ti i K WORLD BOOK to avoid this common defect. Every-day, simple 

 language is used, and technical terms are employed very sparingly. Whenever they 



