Le Bon dealt with all the topics he researched in his books with skill and precision, arriving at wonderful facts. He excelled in his knowledge of man and his expression of the aspects suggested by reason and good taste. Le Bon appeared in everything he wrote as a genius, innovative, free-thinking, independent, and tactful to the end. Therefore, it was right to say: "There is no doubt that Le Bon is the greatest French psychologist of the present time, with the patience he invoked and the insight with which he penetrated the spirit of the age."
In this book, Le Bon investigated the psychological characteristics of races and the change in their morals and ranks, and the disparity of individuals and races, and the formation of historical races, and the elements of civilization being an outward manifestation of the nation's spirit, and the transformation of systems, beliefs, and arts, and the influence of principles in the lives of nations, and the influence of religions in the development of Civilizations, and regarding the great people in the history of nations, and the people of civilizations and their extinction.