The exercise of every sense is pleasurable,--the exercise of sight, hearing, taste, touch, and muscular effort. What can be more pleasurable, for instance, than the feeling of entire health,--health, which is the sum-total of the functions of life, duly performed? "Enjoyment," says Dr. Southwood Smith, "is not only the end of life, but it is the only condition of life which is compatible with a protracted term of existence. The happier a human being is, the longer he lives; the more he suffers, the sooner he dies. To add to enjoyment, is to lengthen life; to inflict pain, is to shorten its duration." Happiness is the rule of healthy existence; pain and misery are its exceptional conditions. Nor is pain altogether an evil; it is rather a salutary warning. It tells us that we have transgressed some rule, violated some law, disobeyed some physical obligation. It is a monitor which warns us to amend our state of living. It virtually says,--Return to nature, observe her laws, 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.