and be restored to happiness. Thus,
paradoxical though it may seem, pain is one of the conditions of the
physical well-being of man; as death, according to Dr. Thomas Brown, is
one of the conditions of the enjoyment of life.

To enjoy physical happiness, therefore, the natural laws must be
complied with. To discover and observe these laws, man has been endowed
with the gift of reason. Does he fail to exercise this gift,--does he
neglect to comply with the law of his being,--then pain and disease are
the necessary consequence.

Man violates the laws of nature in his own person, and he suffers
accordingly. He is idle and overfeeds himself: he is punished by gout,
indigestion, or apoplexy. He drinks too much: he becomes bloated,
trembling, and weak; his appetite falls off, his strength declines, his
constitution decays; and he falls a victim to the numerous diseases
which haunt the steps of the drunkard.

Society suffers in the same way. It leaves districts undrained, and
streets uncleaned. Masses of the population are allowed to live crowded
together in unwholesome dens, half poisoned by the mephitic air of the
neighbourhood. Then a fever breaks out,--or a cholera, or a plague.
Disease spreads from the miserable abodes of the poor into the
comfortable homes of the rich, carrying death and devastation before it.
The misery and suffering incurred in such cases, are nothing less than
wilful, inasmuch as the knowledge necessary to avert them is within the
reach of all.

Wherever any number of persons live together, the atmosphere becomes
poisoned, unless means be provided for its constant change and
renovation. If there be not sufficient ventilation, the air becomes
charged with carbonic acid, principally the product of respiration.
Whatever the body discharges, becomes poison to the body if introduced
again through the lungs. Hence the immense importance of pure air. A
deficiency of food may be considerably less injurious than a deficiency
of pure air. Every person above fourteen years of age requires about six
hundred cubic feet of shut-up space to breathe in during the twenty-four
hours.[1] If he sleeps in a room of smaller dimensions, he will suffer
more or less, and gradually approach the condition of being smothered.

[Footnote 1: Where six hundred cubic feet of space is allowed, the air
requires to be changed, by ventilation, five times in the hour, in order
to keep it pure. The best amount of space to be allowed