Think for a moment of the great agents and engines of our...

Think for a moment of the great agents and engines of our civilization, and then think what shadowy ideas they all once were. The wheels of the steamship turned as swiftly as they do now, but as silent and unsubstantial as the motions of the inventor's thought; and in the noiseless loom of his meditation were woven the sinews of the printing-press, whose thunder shakes the world.