His plan for the work gradually extended to a two-volume compilation on the whole of economic thought; the first volume was published in 1890 to worldwide acclaim that established him as one of the leading economists of his time.

And similarly the principle of substitution is constantly tending by indirect routes to apportion earnings to efficiency between trades, and even between grades, which are not directly in contact with one another, and which appear at first sight to have no way of competing with one another."

- VI.XII.3"The key-notes of the modern movement are the reduction of a great number of tasks to one pattern; the diminution of friction of every kind which might hinder powerful agencies from combining their action and spreading their influence over vast areas; and the development of transport by new methods and new forces.

The macadamized roads and the improved shipping of the eighteenth century broke up local combinations and monopolies, and offered facilities for the growth of others extending over a wider area: and in our own age the same double tendency is resulting from every new extension and cheapening of communication by land and sea, by printing-press and telegraph and telephone."

Marshall was an important part of the "marginalist revolution;" the idea that consumers attempt to adjust consumption until marginal utility equals the price was another of his contributions.