All living organisms are but leaves on the same tree of life. The various functions of plants and animals and their specialized organs are manifestations of the same living matter. This adapts itself to different jobs and circumstances, but operates on the same basic principles. Muscle contraction is only one of these adaptations. In principle it would not matter whether we studied nerve, kidney or muscle to understand the basic principles of life. In practice, however, it matters a great deal.

Here we stand in the middle of this new world with our primitive brain, attuned to the simple cave life, with terrific forces at our disposal, which we are clever enough to release, but whose consequences we cannot comprehend.

Think boldly. Don't be afraid of making mistakes. Don't miss small details, keep your eyes open and be modest in everything except your aims.

Why does man behave like perfect idiot? This is the problem I wish to deal with.

The key to happiness is not to get more, but to enjoy what we have and to fill the empty frame of our lives instead of enlarging it.

This oxidation of hydrogen in stages seems to be one of the basic principles of biological oxidation.

Through the ages, man's main concern was life after death. Today, for the first time, we find we must ask questions about whether there will be life before death.