"Intangibles of this kind, which represent a "conscientious withdrawal of efficiency," an effectual control of the rate or volume of output, are altogether the most common of immaterial assets, and they make up altogether the largest class of intangibles and the most considerable body of immaterial wealth owned. Land values are of much the same nature as these corporate assets which represent capitalized restriction of output, in that the land values, too, rest mostly on the owner's ability to withhold his property from productive use, and so to drive a profitable bargain. Rent is also a case of charging what the traffic will bear; and rental values should properly be classed with these intangible assets of the larger corporations, which are due to their effectual control of the rate and volume of production. And apart from the rental values of land, which are also in the nature of monopoly values, it is doubtful if the total material wealth in any of the civilized countries will nearly equal the total amount of this immaterial wealth that is owned by the country's business men and the investors for whom they do business. Which evidently comes to much the same as saying that something more than one-half of the net product of the country's industry goes to those persons in whom the existing state of law and custom vests a plenary power to hinder production."