Immigration is another topic that might well be considered from the standpoint of variety of ideas. We need as many kinds of people as possible, provided they are good kinds, because their various temperaments and capacities enrich our life. This seems true biologically, as regards diversity of natural stocks, and applies also to the ideals and habits of thought that immigrants bring with them. Our self-esteem naturally depreciates these contributions, but it is fairly clear that after a long course of pioneer life and crude industrialism we are in a position to profit by culture elements that even the peasantry of an older civilization may supply. The Slavs, Italians, Jews, and others who have recently come to America in such numbers have many things to learn from us, but beyond doubt they have also much to teach. Certainly it is a mistake to attempt to suppress foreign customs or languages by any kind of coercion. It is true that a common language, at least, is necessary to assimilation, but this will come naturally if our social attitude is hospitable and our schools efficient. Moreover, a too sudden or compulsory break with the past is a bad thing, impairing self-respect and stability of character. Those who cherish what is best in the old life will make all the better members of the new. Such trouble as we have had with our immigrants, in regard to assimilation, is almost negligible, compared with the complete failure of harsher methods in Europe. The larger discussion involves a struggle for survival among innumerable ideas, springing from the innumerable diversities of person, class, and situation. One naturally inquires what causes some of these ideas to survive and prevail rather than others. What makes the success or failure of a principle or a project? Some writers will answer this question for us by pointing to specific factors which they think are decisive—though they by no means agree as to what these are—but I take it that the determining agent is nothing less than the total situation, which we must grasp as a whole in order to see the trend of things. The life of an idea depends upon the degree and manner of its working in the actual complex state of the mind of the people, consisting largely of impulses, habits, and traditions whose sources are remote and obscure. Take, for example, the change in our ideas regarding the functions and problems of women, indicated by the contrast between the literature of the nineteenth century and that of to-day. Certain reasons can be given for it, such as the growing self-dependence and class-consciousness of women, their employment in modern industry and the popularization of social and biological science. These and many other elements are worked up by discussion, producing an atmosphere in which the conventions of fifty years ago seem prudish and absurd. A novel, a play, or a social programme will succeed now which our fathers and mothers would have suppressed.