capable of turning a mill; but a horse cannot turn it without somebody to drive and watch him. On the other hand, there is some bodily ingredient in the labour most purely mental, when it generates any external result. Newton could not have produced the Principia without the bodily exertion either of penmanship or of dictation; and he must have drawn many diagrams, and written out many calculations and demonstrations, while he was preparing it in his mind. Inventors, besides the labour of their brains, generally go through much labour with their hands, in the models which they construct and the experiments they have to make before their idea can realize itself successfully in act. Whether mental, however, or bodily, their labour is a part of that by which the production is brought about. The labour of Watt in contriving the steam-engine was as essential a part of production as that of the mechanics who build or the engineers who work the instrument; and was undergone, no less than theirs, in the prospect of a remuneration from the produce. The labour of invention is often estimated and paid on the very same plan as that of execution. Many manufacturers of ornamental goods have inventors in their employment, who receive wages or salaries for designing patterns, exactly as others do for copying them. All this is strictly part of the labour of production; as the labour of the author of a book is equally a part of its production with that of the printer and binder.
In a national, or universal point of view, the labour of the savant, or speculative thinker, is as much a part of production in the very narrowest sense, as that of the inventor of a practical art; many such inventions having been the direct consequences of theoretic discoveries, and every extension of knowledge of the powers of nature being fruitful of applications to the purposes of outward life. The electromagnetic telegraph was the wonderful and most unexpected consequence of the experiments of Œrsted and the mathematical investigations of Ampère: and the modern art of navigation is an unforeseen emanation from the purely specu-
