Any attempt to shape the world and modify human personality in order to create a self-chosen pattern of life involves many unknown consequences. Human destiny is bound to remain a gamble, because at some unpredictable time and in some unforeseeable manner nature will strike back. The multiplicity of determinants which affect biological systems limits the power of the experimental method to predict their trends and behavior.

Any attempt to shape the world and modify human personality in order to create a self-chosen pattern of life involves many unknown consequences. Human destiny is bound to remain a gamble, because at some unpredictable time and in some unforeseeable manner nature will strike back. The multiplicity of determinants which affect biological systems limits the power of the experimental method to predict their trends and behavior.

... each type of civilization has had diseases peculiar to it and at each period the various social groups in any community also have differed in this regard.

As long as mankind is made up of independent individuals with free will, there cannot be any social status quo. Men will develop new urges, and these will give rise to new problems, which will require ever new solutions. Human life implies adventure, and there is no adventure without struggles and dangers.

To ward off disease or recover health, people as a rule find it easier to depend on healers than to attempt the more difficult task of living wisely.

Pathological states are the consequence of several determinate factors acting simultaneously...The manifestations of any given agent differ profoundly from one person to another. ...Each noxious agent can express itself by a great variety of different pathological states. ...Different agents can elicit similar reactions. ...The total environment and the (interior medium) constitute a multifactorial system.

The mechanisms of vis medicatrix naturæ—the most healing power of nature—are so effective that most diseases are self-terminating.