The poet-philosopher Goethe remarks that every brain-worker should consult his sanitary interests by following some mechanical trade as a by-occupation, and the successor of Frederic the Great made that advice a pretext for establishing the rule that every prince of the House of Prussia must serve an apprenticeship at some handicraft. Some of the uniformed youngsters accordingly learn printing, others bookbinding, but about four out of five prefer a curriculum in a carpenter's shop. A hundred years ago the Berlin wits used to hint that the by-law in question might prove useful under circumstances that obliged a good many refugees from neighboring France to try their hands at the unaccustomed occupation of useful work, but the rule is still in force, and none of the royal blue-coats have been the worse for the investiture of a carpenter's apron. Joiner's work: sawing, jack-planing, and hammering exercises nearly every muscle of the human body, and has the incidental advantage of a pastime that grows on the habit and can become a passion, like gardening and watchmaking.

And not all "exercise with a useful by-purpose" can be recommended from that point of view. There are some extremely utilitarian occupations that lack the spice of variety and a personal interest. In some cities of British India, where labor is cheap and coal very dear, hundreds of vagabonds are often roped in to operate the machinery of a large workshop on the treadmill plan; but in spite of sanitary precautions a wheel-treader every now and then steps down and out with the unfeigned symptoms of complete exhaustion. "I tried it, for the fun of it," says Sir Samuel Baker, "but was unable to persist for more than ten minutes, though I am pretty sure that in my Ceylonese mountain camp the excitement of a boar-chase often enabled me to exert the tenfold amount of muscular effort without any conscious trace of fatigue."

Every well-arranged household, in fact, should have an indoor sanitarium in the form of a general repair-shop, or Jack-of-all-trades resort. From an artistic point of view the products of the establishment may prove shameful failures, but they will save doctor's bills and perhaps police-court fines.

In freeing themselves from the bonds of an unworthy attachment," says Madame de Sévigné, "men have one great advantage: they can plunge into business, and forget;"—and a rush into a convenient workshop will often solve the problem of fighting clown minor temptations that cannot be exorcised by study.

Combined with wholesome food and steady habits, indoor work has more than once enabled city-dwellers to emulate the physical prowess of rustics. Frederic Barbarossa's armies had been recruited among the bare-fisted peasantry of the South-German highlands but on the battlefield of Legano were crushingly defeated by the trainbands of some fourteen Italian cities. Roman legionaries held their own against the giants of the Teutonic forests, and the levies of the Hanseatic League prevailed against the federation of the iron-clad cavaliers that had for centuries treated them as an inferior species of bipeds. Lionheart Richard came to grief in a siege, and his German peer, Eberhart Longbeard of Wirtemberg was terribly beaten by the home-guards of a little manufacturing town.

"Wie haben da die Gerber so meisterlich gegerbt;
  Wie haben da die Farber so blutig roth gefarbt"—
        "How the tanners plied their trade,
          How the dyers dyed so red!"

—and all that in spite of the fact that the artisans of the Middle Ages were physically handicapped by the unsanitary condition of their streets and dwellings.