The function of the directive faculties, as applied thus to the operations of modern labour, can perhaps be most easily illustrated by the case of a printed book. Let us take two editions of ten thousand copies each, similarly printed, and priced at six shillings a copy; the one being an edition of a book so dull that but twenty copies can be sold of it, the other of a book so interesting that the public buys the whole ten thousand. Now, apart from its negligible value as so many tons of waste paper, each pile of books represents economic wealth only in proportion to the quantity of it for which the vendors can find purchasers. Hence we have in the present case two piles of printed paper which, regarded as paper patterned with printer's ink, are similar, but one of which is wealth to the extent of three thousand pounds, while the other is wealth to the extent of no more than six pounds. And to what is the difference between these two values due? It obviously cannot be due to the manual labour of the compositors, for this, both in kind and quantity, is in each case the same. It is due to the special directions under which the labour of the compositors is performed. But these directions do not emanate from the men by whose hands the types are arranged in a given order. They come from the author, who conveys them to the compositors through his manuscript; which manuscript, considered under its economic aspect, is neither more nor less than a series of minute orders, which modify from second to second every movement of the compositors' hands, and determine the subsequent results of every impress of the type on paper; one mind thus, by directing the labour of others, imparting the quality of much wealth or of little or of none, to every one of the ten thousand copies of which the edition is composed. Similarly when a man invents, and brings into practical use, some new and successful apparatus such, let us say, as the telephone, the same situation repeats itself. The new apparatus is an addition to the world's wealth, not because so many scraps of wood, brass, nickel, vulcanite, and such and such lengths of wire are shaped, stretched, and connected with sufficient manual dexterity--for the highest dexterity is very often employed in the making of contrivances which turn out to be futile--but because each of its parts is fashioned in obedience to certain designs with which this dexterity, as such, has nothing at all to do. The apparatus is successful, and an addition to the world's wealth, because the designs of the inventor, just like the author's manuscript, constitute a multitude of injunctions proceeding from a master-mind, which is not the mind of those by whose hands they are carried into execution.