What is it that binds all these persons together? A little tarrying in the Treasurer's office will answer this question for our observer and for us. He will find it to be the second kind of Buying and Selling. At stated times the Treasurer pays the salary of the Agent, and his own. He pays the wages of the Overseers and the wages of all the Operatives and Laborers,--men and women and children. Here he finds a buying and selling on a great scale not of material commodities as before, but of personal services of all the various kinds. Every man and woman and child connected with the factory and doing its work sells an intangible personal service to the "Company" and takes his pay therefor, which last is a simple buying on the part of the unseen employers. Here, then, in this mill is a single specimen of this buying and selling of personal services, which is going on to an immense extent and in every possible direction in each civilized country of the world, and everywhere to an immensely increased volume year by year. Clergymen and lawyers and physicians and teachers and legislators and judges and musicians and actors and artisans of every name and laborers of every grade sell their intangible services to Society, and take their pay back at the market-rate. The aggregate value of all these services sold in every advanced country is probably greater than the aggregate value of the tangible commodities sold there. At any rate, both classes alike, commodities and services, are bought and sold under substantially the same economic principles. The inductive appetite in intelligent persons, that is to say, their desire to classify facts and to generalize from particulars, almost always grows by what it feeds on; and our supposed observer will scarcely rest contented until he has taken up at least one more stand-point, from which to observe men's Buying and Selling. Suppose now he enter for this purpose on any business-day morning the New York Clearing-House. He will see about 125 persons present, nearly one half of these bank clerks sitting behind desks, and the other half standing before these desks or moving in cue from one to the next. The room is perfectly still. Not a word is spoken. The Manager of the Clearing with his assistant sits or stands on a raised platform at one end of the room, and gives the signal to begin the Exchange. No commodities of any name or nature are within the field of view. The manager indeed and his assistant and two clerks of the establishment who sit near him are in receipt of salaries for their personal services, and all the other clerks present receive wages for their services from their respective banks, but the exchange about to commence is no sale of personal services any more than it is a sale of tangible commodities. It is however a striking instance of the buying and selling of some valuables of the third and final class of valuable things.