the mind every teacher is well
aware that time is an essential factor. It is necessary to _live_ with a
study for hundreds or thousands of hours before the mind can assimilate
as much of the subject as it may need; and so it is necessary to live in
exercise during a thousand hours of every year to make sure of the
physical benefits. Even the fresh air itself requires time to renovate
our blood. The fresh air cannot be concentrated; and to breathe the
prodigious quantities of it which are needed for perfect energy, we must
be out in it frequently and long.

The inhabitants of great cities have recourse to gymnastics as a
substitute for the sports of the country. These exercises have one
advantage--they can be directed scientifically so as to strengthen the
limbs that need development; but no city gymnasium can offer the
invigorating breezes of the mountain. We require not only exercise but
exposure--daily exposure to the health-giving inclemencies of the
weather. The postman who brings my letters walks eight thousand miles a
year, and enjoys the most perfect regularity of health. There are
operatives in factories who go through quite as much bodily exertion,
but they have not his fine condition. He is as merry as a lark, and
announces himself every morning like a bearer of joyful tidings. What
the postman does from necessity an old gentleman did as regularly,
though more moderately, for the preservation of his health and
faculties. He went out every day; and as he never consulted the weather,
so he never had to consult the physicians.

Nothing in the habits of Wordsworth--that model of excellent habits--can
be better as an example to men of letters than his love of pedestrian
excursions. Wherever he happened to be, he explored the whole
neighborhood on foot, looking into every nook and cranny of it; and not
merely the immediate neighborhood, but extended tracts of country; and
in this way he met with much of his best material. Scott was both a
pedestrian and an equestrian traveller, having often, as he tells us,
walked thirty miles or ridden a hundred in those rich and beautiful
districts which afterwards proved to him such a mine of literary wealth.
Goethe took a wild delight in all sorts of physical exercise--swimming
in the Ilm by moonlight, skating with the merry little Weimar court on
the Schwansee, riding about the country on horseback, and becoming at
times quite outrageous in the rich exuberance of his energy.