ABSTRACT
The value of the marginal social net product of any quantity of resources employed in any use or place is simply the sum of money which the marginal social net product is worth in the market. In some conditions this is equal to, in some it is greater than, in others it is less than the marginal social net product. The product of that last unit of capital is the difference between what the road actually produces and what it would have produced if it had been made one degree poorer. The marginal net product of a factor of production is the difference that would be made to the aggregate product by withdrawing any unit of the factor. The marginal social net product is the total net product of physical things or objective services due to the marginal increment of resources in any given use or place, no matter to whom any part of this product may accrue.
