By means of his intelligence he can change the environment.

He is able to resist the action of cold by means of houses, fire and clothing; without such power of intelligent creation of the immediate environment the climatic area in which man could live would be very narrow.

Just as disease can be acquired by an unfavorable environment, man can so adjust his environment to an injury that harmony will result in spite of the injury.

The environment which is necessary to compensate for an injury may become very narrow.

For an individual with a badly working heart more and more restriction of the free life is necessary, until finally the only environment in which life is even tolerably harmonious is between blankets and within the walls of a room.
The various conditions which may act on an organism producing the changes which are necessary for disease are manifold.