Nature always strikes back. It takes all the running we can do to remain in the same place.

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.

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.

There is an unbroken continuum from the wisdom of the body to the wisdom of the mind, from the wisdom of the individual to the wisdom of the race.

With reference to life there is not one nature; there are only associations of states and circumstances, varying from place to place and from time to time.

Man not only survives and functions in his environment, he shapes it and he is shaped by it.

Eradication of microbial disease is a will-o'-the-wisp; pursuing it leads into a morass of hazy biological concepts and half truths.