I have already alluded to the stress laid by Socialists on the fact that different individuals in different parts of the world often make the same discoveries at almost the same time; and I pointed out that whatever this might teach us, applied only to a small minority of persons, and had no reference whatever to the great mass of the race. But Socialists very frequently put their view in a form even more exaggerated than that which I thus criticised. ◆¹ They use language which implies that the whole mass of society moves forward together at the same intellectual pace; and that discoverers and inventors merely occupy the position of persons who chance to be walking a few paces in advance of the crowd, and who thus light upon new processes or machines like so many nuggets lying and glittering on the ground, which those who follow would have presently discovered for themselves; or, again, they are represented as persons who are merely the first to utter some word or exclamation which is already on the lips of everybody. Let us, then, take the three great elements which go to make up the industrial prosperity of this country—the manufacture of iron, the manufacture of cotton, and the development of the steam-engine, and see how far the history of each of these lends any support to the theory just mentioned. [Sidenote ◆1 The modern development of the iron industry dependent on the use of coal in place of wood.] [Sidenote ◆2 The discovery of how to use coal for this purpose due to a few individuals, whose labours were either secret, or bitterly opposed by all who knew of them. Chief amongst these were] We will begin with the manufacture of iron. Ever since man was acquainted with the use of this metal till a time removed from our own by a few generations only, ◆¹ its production from the ore was dependent entirely upon wood, which alone of all fuels—so far as knowledge then went—had the chemical qualities necessary for the process of smelting. The iron industry in this country was therefore, till very recently, confined to wooded districts, such as parts of Sussex and Shropshire; and so large, during the seventeenth century, was the consumption of trees and brushwood, that the smelting furnace came to be considered by many statesmen as the destroyer of wood, rather than as the producer of metal. ◆² This view, indeed, can hardly be called exaggerated; for by the beginning of the century following the wood available for the furnaces was becoming so fast exhausted that the industry had begun to dwindle; and but for one great discovery it would have soon been altogether extinguished. This was the method of smelting iron with coal. Now to what cause was this discovery due? The answer can be given with the utmost completeness and precision. It was due to the Ability of a few isolated individuals, whose relation to their contemporaries and to their age we will now briefly glance at.