Let us now turn to invention and applied science; and the history of social progress, as connected with and derived from them, will show the same two elements—the unintended and the intended, similarly related and similarly coexistent. A brilliant illustration of this fact is provided for us, in one of his books, by Mr. Herbert Spencer, though he himself, with a curious blindness and perversity, uses it not to illustrate but to obscure the point on which we are now dwelling. The illustration referred to is the history of the press by which the _Times_ is printed, which implement, according to Mr. Spencer, is the result altogether of evolution. “_In the first place_,” he says, “_this automatic printing machine is lineally descended from other automatic printing machines . . . each pre-supposing others that went before. . . . And then, in tracing the more remote antecedents, we find an ancestry of hand printing presses._” He further points out that this press implies not only an ancestry of former presses, but also the existence of the machinery used in making it, and again how this machine-making machinery has a distinct ancestry of its own, which includes the fact of the abundance of iron in England. Geometry, physics, chemistry also, he says, played their part in the process; and he winds up by referring to purely social causes. {102} Why, he asks, was the Walter press produced? In order that “_with great promptness_” it might “_meet an enormous demand_.” It is difficult to imagine a better illustration than this of the part played by evolution in the domain of mechanical invention. It is perfectly evident that the mass of discoveries and inventions which preceded and paved the way for the final invention in question were due to men who had no idea in their heads of such a machine as a steam-driven printing press at all. When printing was first invented, steam-power was undreamed of. When the steam-engine was being perfected as a means of driving machinery, the inventors had no specific intention of applying this force to the printing press. The men whose genius and energy in the seventeenth and eighteenth centuries laid the foundation of the English iron trade, and with it, as Mr. Spencer says, the foundation of “_machine-making generally_,” in all probability never even saw a newspaper, and could not have conceived the possibility of collecting enough news daily to fill as much as one page of the _Times_. The mathematicians and chemists to whose work Mr. Spencer alludes most probably never gave a thought to the practical application of their discoveries, and knew as little of the process of printing as they did of Chinese grammar. But let us give to these facts all the weight we can. Let us accept the antecedents that made the Walter press possible as not only sequences but also concurrences of the unintended; and yet the part played {103} by the great man remains as essential, and remains as large as ever.