th the young,
and if not followed to excess are most advantageous. The walk in the
open air is life to many. But boy or man can never be what they ought
to be unless they take exercise regularly and judiciously, take it not
to exhaust but to refresh and stimulate. It strengthens the nerve and
clears the brain and fits for work.

3. _Rest_.--Man needs a certain amount of repose to sustain his frame
in full vigor. Some need more, some need less. We must find out for
ourselves what we need and take it. Lack of sleep is especially a
great waste of vitality. Here also we must exercise our judgment as to
the amount of sleep we require. One needs a great deal; another can do
with very little. Early rising, which has been much recommended, is
only good for those who go early to bed. If one is compelled to sit up
late he should sleep late in the morning. It is no virtue on the part
of anyone to get up early unless he has slept enough. _That_ he must
do if he is to have health. A man who would be a good worker must see
to it that he is a good sleeper; and whoever, from any cause, is
regularly diminishing his sleep is destroying his life. Shakespeare
has well described the blessing of sleep when he says:

Sleep that knits up the ravelled sleeve of care,
The death of each day's life, sore labor's bath,
Balm of hurt minds, great Nature's second course,
Chief nourisher in life's feast.

These are but _hints_ in connection with a great subject. A few brief
rules may be given of a general character:

1. Take exercise every day in the open air if possible, and make it a
recreation and not merely a duty.

2. Eat wholesome food, drink pure water.

3. Let your house and room be well ventilated.

4. Take time enough for sleep. Do not worry.

5. Watch yourself, but not too closely, to find out what exercise,
air, diet, etc., agrees with you. No man can be a rule for another.

6. If you consult a physician, it is better to do it before you are
unwell than later.[3]

We close this chapter with the powerful words of Thomas Carlyle,
addressed to the students of the University of Edinburgh: "Finally, I
have one advice to give you which is practically of very great
importance. You are to consider throughout much more than is done at
present, and what would have been a very great thing for me if I had
been able to consider, that health is a thing to be attended to
continually; that you are to regard i