co-operated in the invention of each of these machines which embody the genius of man.
Thousands of writers, of poets, of scholars, have laboured to increase knowledge, to dissipate error, and to create that atmosphere of scientific thought, without which the marvels of our century could never have appeared. And these thousands of philosophers, of poets, of scholars, of inventors, have themselves been supported by the labour of past centuries. They have been upheld and nourished through life, both physically and mentally, by legions of workers and craftsmen of all sorts. They have drawn their motive force from the environment.
The genius of a Séguin, a Mayer, a Grove, has certainly done more to launch industry in new directions than all the capitalists in the world. But men of genius are themselves the children of industry as well as of science. Not until thousands of steam-engines had been working for years before all eyes, constantly transforming heat into dynamic force, and this force into sound, light, and electricity, could the insight of genius proclaim the mechanical origin and the unity of the physical forces. And if we, children of the nineteenth century, have at last grasped this idea, if we know now how to apply it, it is again because daily experience has prepared the way. The thinkers of the eighteenth century saw and declared it, but the idea remained undeveloped, because the eighteenth century had not grown
