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HINGS marvelous there are many," says the Attic dramatist, "but among them all naught moves more truly marvelous than man." And, indeed, when one begins seriously to think it over, there is no machine in all the world one-half, nay one-millionth part, so extraordinary in its mode of action as the human brain. Minutely constructed, inscrutable in all its cranks and wheels, composed of numberless cells and batteries, all connected together by microscopically tiny telegraphic wires, and so designed (whether by superior intelligence or evolutionary art) that every portion of it answers sympathetically to some fact or energy of the external universe—the human brain defies the clumsy analysis of our carving-knife anatomists, and remains to this day a great unknown and almost unmapped region, the terra incognita of modern physiology. If you look into any one of the ordinary human machines, with its spokes and cogs, its springs and levers, you can see at once (at least, if you have a spark of native mechanical intelligence within you) how its various portions are meant to run together, and what is the result, the actual work, to be ultimately got out of it. But not the profoundest microscopist, not the acutest psychologist, not the most learned physiologist on earth could possibly say, by inspecting a given little bit of the central nervous mechanism of humanity, why the excitation of this or that fragment of gray matter should give rise to the picture of a brown umbrella or the emotion of jealousy, why it should rather be connected with the comprehension of a mathematical problem than with the consciousness of pain or the memory of a gray-haired, military-looking gentleman whom we met three years ago at an hotel at Biarritz.

Merely to state these possible alternatives of the stimulation of a portion of the brain is sufficient to bring up vividly into view the enormous and almost inconceivable complexity of that wonderful natural mechanism. Imagine for a moment a machine so delicate that it is capable of yielding us the sensation of a strawberry-ice, the æsthetic delight of a beautiful picture, the intellectual perception of the equality of the angles at the base of an isosceles triangle, the recollection of what we all said and did the day we went for that picnic to the Dolgelly waterfalls, the vague and inconsistent dissolving views of a disturbed dream, the pain of toothache, and the delight at meeting once more an old friend who has returned from India. The very mention of such a complicated machinery, let alone the difficulty of its possession of consciousness, is enough to make the notion thus nakedly stated seem wild and absurd. Yet there the machine actually is, to answer bodily for its own possibility. You can not cavil at the accomplished