Don't become a mere recorder of facts, but try to penetrate the mystery of their origin.

But man has still another powerful resource: natural science with its strictly objective methods.

Men are apt to be much more influenced by words than by the actual facts of the surrounding reality

Possibilities are like the wings of birds; they allow man to soar and to climb to the heavens. And facts are like the atmosphere against which those wings must beat, and without which the soaring bird will surely plummet back to earth.

When the dog is repeatedly teased with the sight of objects inducing salivary secretion from a distance, the reaction of the salivary glands grows weaker and weaker and finally drops to zero.

As was to be expected, the discovery of the nervous apparatus of the salivary glands immediately impelled physiologists to seek a similar apparatus in other glands lying deeper in the digestive canal.

I am convinced that an important stage of human thought will have been reached when the physiological and the psychological, the objective and the subjective, are actually united, when the tormenting conflicts or contradictions between my consciousness and my body will have been factually resolved or discarded.