What would be the actual money cost of providing for individual differences in capacities, general and special? Few data to answer this question have been furnished. In Winnetka the cost of education is reported as not increased. This condition is doubtless exceptional. As previously stated, the money cost of individualizing education for the feeble-minded has been considerable. We have the figures from Cincinnati, and we derive from them that the cost of educating a feeble-minded child (one falling into the lowest one or two per cent in the distribution of general intelligence) in a special class, is over twice as great per annum as is the cost of educating an average child in the regular grades. For a feeble-minded child in a special class in Cincinnati, during the year 1917 to 1918, the money cost per annum was $83, while for a typical child in the regular grades it was $35. The increased cost results from the fact that when education is individualized, the number of pupils occupying a room and taught by a teacher is about fifteen, instead of the regular number of thirty to fifty. If, roughly, 20 per cent of all pupils deviate from the typical so extremely as to require a considerable amount of individual instruction for their welfare, it is difficult to see how they may be well served without a considerable increase in the money cost of education. Can the public afford to pay more than it now does? Investigations to answer this question are under way on a large scale. We need to know what our country can now pay, in order that we as educators may not commit the folly on the one hand of urging unwarrantable expenditure, nor on the other hand of failing to ask the appropriation of all that can be spared for the development of individual capacity in the nation’s children. VII. THE PROBABLE REWARDS OF INDIVIDUALIZING EDUCATION Even the money returns from scientifically differentiated education would probably be great, aside from the increase in children’s happiness, in teachers’ enjoyment, and in adults’ satisfaction. The tangible values of individualized training might be nearly as great as its intangible values. When we reflect closely upon the source of wealth, we see that it comes from the attack of intellect upon the environment. Apes have no wealth. Man has wealth only in so far as he acts upon selective thinking in regard to his environment. A society gains wealth only in so far as it permits and encourages the use of innate capacities for attack upon the environment, which lie unequally distributed throughout the juvenile population. Any theory of wealth that fails to ground itself upon this fact will but destroy those who seek to practice it. No nation has ever yet shown what the full reward might be of adapting education to individual differences. Such a demonstration has been impossible hitherto, if for no other reason than that there was no known method of gauging children’s abilities scientifically.