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.

Learn the ABC of science before you try to ascend to its summit.

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.

Gradualness, gradualness, and gradualness. From the very beginning of your work, school yourself to severe gradualness in the accumulation of knowledge.

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.

While you are experimenting, do not remain content with the surface of things.