Thus, in the school, it is for the individualization of educational diagnosis and of educational treatment that the home visitor exists. The educational authorities become aware that they need to understand certain children or all the children of a group more in detail--each child's needs, difficulties, sources of retardation. This _educational diagnosis_ is made possible through the home visitor's study of the child in the home and out of school hours. There follows a greater individualization of _educational treatment_. The teacher is enabled, through the reports of the home visitor, to fit his educational resources more accurately to the particular needs of the scholar, so that they will do the most good. In the juvenile courts the judge needs to understand more in detail the child's individual characteristics, the circumstances, the temptations, which preceded and accompanied the commission of the offence which now brings the culprit before him. This is _penological diagnosis_, and the court visitor or probation officer, sometimes simply called the social worker, makes a study of the law-breaker in his home and in relation to all the influences, physical or moral, which may help to explain the commission of the particular offence which has brought him into trouble. All this leads to the greater precision of _penological treatment_. Understanding more in detail why this particular boy has committed this particular theft, how he differs from other boys who have stolen, the judge is much more likely to choose wisely those measures of treatment which in the long run will do most to reëstablish the individual as a healthy member of society. In the factory the object of the employer in setting a home visitor or welfare worker at work is to create the maximum of satisfaction and good spirit among his employees, whereby each will do his best work and be as little likely as possible to change his employment. In the old days, when shops were small and the employer could know his employees personally, no intermediary such as a home visitor was necessary. The employer could keep human touch with his men. He could know not merely the amount of work done by each man, but something of the circumstances of his life, something of his personality, his adventures and misfortunes, so that help could be extended to him from time to time when special need occurred. It is only when the workshop has grown to the enormous size familiar in modern industrial plants that this relation of employer and employee has to be supplemented through the mediating offices of the home visitor.