A crucial experiment would be to take a large number of very young children of the lower classes and, after placing them in the most favorable environment obtainable, to compare their later mental development with that of children born into the best homes. No extensive study of this kind has been made, but the writer has tested twenty orphanage children who, for the most part, had come from very inferior homes. They had been in a well-conducted orphanage for from two to several years, and had enjoyed during that time the advantages of an excellent village school. Nevertheless, all but three tested below average, ranging from 75 to 90 I Q. The impotence of school instruction to neutralize individual differences in native endowment will be evident to any one who follows the school career of backward children. The children who are seriously retarded in school are not normal, and cannot be made normal by any refinement of educational method. As a rule, the longer the inferior child attends school, the more evident his inferiority becomes. It would hardly be reasonable, therefore, to expect that a little incidental instruction in the home would weigh very heavily against these same native differences in endowment. Cases like the following show conclusively that it does not:-- X is the son of unusually intelligent and well-educated parents. The home is everything one would expect of people of scholarly pursuits and cultivated tastes. But X has always been irresponsible, troublesome, childish, and queer. He learned to walk at 2 years, to talk at 3, and has always been delicate and nervous. When brought for examination he was 8 years old. He had twice attempted school work, but could accomplish nothing and was withdrawn. His play-life was not normal, and other children, younger than himself, abused and tormented him. The Binet tests gave an I Q of approximately 75; that is, the retardation amounted to about two years. The child was examined again three years later. At that time, after attending school two years, he had recently completed the first grade. This time the I Q was 73. Strange to say, the mother is encouraged and hopeful because she sees that her boy is learning to read. She does not seem to realize that at his age he ought to be within three years of entering high school. The forty-minute test had told more about the mental ability of this boy than the intelligent mother had been able to learn in eleven years of daily and hourly observation. For X is feeble-minded; he will never complete the grammar school; he will never be an efficient worker or a responsible citizen.