The principles of regeneration by natural hygiene may be summed up in Dr. Hufeland's advice, to "re-establish, as far as practicable, the conditions to which our organism became adapted during the infinite series of ages preceding the era of indoor-life and made-dishes." The human constitution—physical and moral—was never intended for the sloth of the domestic habits enforced by our sabbatharian civilization. Man's predecessors in the scale of organic evolution were the most restlessly active of all vertebrate animals. Our Darwinian cousins pass their life in the gymnasia of nature—the tree-tops of the tropical virgin-woods; their meals, courtships, and forays alternate with acrobatic exploits; they build no nests; except an occasional rain-shelter, and carry their young in their migrations from forest to forest.

Almost equally active, and even more athletic, man-like creatures inhabited this planet for a period variously estimated from 25,000 to half a million years. Human skeletons have been found among the strata of former geological ages and associated with the bones of such prehistoric animals as mammoths and cave-bears. They were tree-climbers and tree-food eaters, at first, those semi-human progenitors of ours, and in their encounters with the giant-cats of the tropics developed that dread of darkness and night-hags still haunting our mental condition, with all its instinctive love of forest-life. Venturing further and further from their equatorial birthlands, our primitive ancestors became hunters; then nomadic herders, and finally stock-farmers, trying their luck with various methods of agriculture.

During that infinite series of generations the beings that evolved our organism may have strayed into strange forms of idolatry and refuted the belief in the universality of moral institutions; but they certainly did not fail to worship the goddess of health in her own temples. They were runners, swimmers, leapers, hill-climbers, wrestlers, boxers, and spearmen; outdoor exercise yielded them both the means of life and the opportunities for recreation. And it would be a mistake to suppose that the brief era of indoor life had modified our physical constitution in any essential respect. Rivers run most easily in their ancient channels. Remedy-mongers have tried the effect of concentrated food—pure fat, sugar, albumen, and so forth, but it was found that the human stomach preferred more concrete substances. "Whole-wheat bread." with all its innutritive admixtures, is more digestible than pure starch.

Chemically the reason why is not quite clear, but we may suspect that it has a good deal to do with habits formed during the long ages preceding the advent of Liebig's food extracts.

And Nature declines to ratify the contract of kid-gloved brain-workers with the inventors of labor-saving machinery. Intellectual development, to be sure, is the quintescence of all that distinguishes man from his brute fellow-creatures; but beings of our species cannot thrive on metaphysics alone, any more than on Dr. Bernard's Elixir of Life. To avoid dyspepsia, insomnia, hemorrhoids, and sick headaches the Trismegistus of Science has now and then to descend from his study and exercise his motive muscles in the playgrounds of the hirsute anthropoids. Dr. Boerhave's remark that we ought to substitute mechanical for chemical remedies has been paraphrased in the apothegm that "patients might walk away from a good many diseases." Pedestrianism is, indeed, the readiest of all forms of active exercise—doubly effective to burden-carriers, though a health-seeker need not take up his whole bed to walk. A stout overcoat in winter and a market-basket in summer are enough to outweigh the influence of habit which in the course of years might otherwise modify the efficiency of the prescription. An old physician of my acquaintance often repeats his assertion that the best advice a doctor could give to a friend (as distinct from a fee-paying patient) would be to choose his dwelling on some out-of-the-way hill-top, or similar location, at a safe distance from the temptation of the street-car lines, and to readopt the good old democratic habit of doing his own shopping.

Where street-cars reach," he says, "there will be always a pretext for using them, in spite of solemn pledges to the contrary. It will be storms in winter and heat in summer, or special hurry, where meteorological excuses fail. But in the form of Hobson's choice an excellent movement-cure remedy will get a chance to prove itsefficacy. The walking-habit may ruin a dozen extra pair of shoes per year, and the random shopper is apt to fare worse than the patron of a grocery-wagon; but he is sure to bring home a cargo of health."

A keen appetite for supper, for instance, and a fair chance for a good night's rest. The effect of pedestrianism as a specific for the cure of insomnia can be tested by the simple plan of an occasional intermission. A stay-at-home day being pretty sure to be followed by twice the usual number of sleepless hours.

The organs of the human body are weakened by disuse and invigorated by active service; unexercised muscles become flabby, teeth decay upon a diet of pap; our very hair dies and drops like dead leaves if the constant wearing of hats and night-caps makes it superfluous. And to a quite unsuspected degree the same holds good of our respiratory organs. Exercise that makes the lungs work to the limit of their capacity tends to gradually enlarge that limit. Consumptives not too far advanced toward the stage of total collapse may purchase a new lease of life by exercise stimulating the action of the torpid lungs. A few years ago an emaciated Canadian miner came South for his health and located a small placer claim on the plateau of "Fort Mountain" in Murray County, Georgia. The mountain is a mile high—a cloud-capped outpost of the Southern Alleghanies, and the up-trip, with a few dozen eggs from the next valley farm, obliged the miner to stop every few minutes to keep his chest from bursting; but before the end of the year he was able to make the same trip, without a stop, with a bushel-bag full of cornmeal. The waste from the ravages of the tubercle microbes can perhaps never be repaired but the healthy tissue of the remaining portion of the lung is susceptible both of expansion and invigoration. The lungs expand and contract with the chest.

If three sisters marry on the same day—the first a ferryman, and learns to row a boat; the second a tailor and takes to tight lacing; the third a grocer and tends his shop, an autopsy would show that in twenty years after their separation the ferrywoman's lungs have grown fifty per cent larger than the shopkeeper's and fully twice as large as the dressmaker's.