It is this same process of evolution, the same heaping-up of groups till finally they become unmanageable, which has led to the employment of the social worker in other institutions. It is because the schoolmaster must teach so many that he can no longer know his pupils and their families individually that he has to employ the home visitor to keep him better in touch with them. It is because the judge tries so many prisoners that he cannot grasp and pursue all the detailed characteristics of those who come before him for judgment that he is compelled to get them at second-hand from a home visitor. So finally when we approach the reasons for which the medical home visitor has come in the better dispensaries of the United States to be an essential part of the institution, we find that the unmanageable increase in the number of patients to be treated by the doctor is one of the chief reasons why the home visitor has become necessary. In the old days and in country practice especially, it was doubtless possible for the doctor to follow the lives of his patients individually as acquaintances, and through many years, to watch the growth and development of families, to know their members as a friend and not merely in a professional capacity. He would meet them as a neighbor, in church, in town meetings, in agricultural fairs, in village sports and holidays. Thus he would touch the lives of his fellow citizens on many sides, and when he came to their aid in his narrower professional capacity he could supplement his diagnostic findings and his therapeutic resources out of the wealth of knowledge which years of association with them outside the sick-room had furnished him. II But in the evolution of the particular type of social worker who is the subject of this book, the home visitor connected with a dispensary, there are other forces besides those described above, other motives besides that common to the rise of all the types of home visitors in all the other institutions named. For in the dispensary, not only has the number of applicants greatly increased, but it has increased because people realized that there was much more to be obtained by going to a dispensary than was formerly the case. The development of medical science and of the resources of diagnosis and treatment which can now be put at the service of the dispensary patient, has served to attract more patients there. But these new resources have also complicated the work of the physician in a dispensary, and made it more difficult for him to remember each patient and all the details about each patient as the physical, chemical, psychological, biological facts emerge in the complex ramifications of modern diagnosis and treatment.