Plasticity, then, in the wide sense of the word, means the possession of a structure weak enough to yield to an influence, but strong enough not to yield all at once. Each relatively stable phase of equilibrium in such a structure is marked by what we may call a new set of habits.

Agisci come se quel che fai, facesse la differenza. La fa!

The unrest which keeps the never stopping clock of metaphysics going is the thought that the nonexistence of this world is just as possible as its existence.

You make a great, very great mistake, if you think that psychology, being the science of the mind's laws, is something from which you can deduce definite programmes and schemes and methods of instruction for immediate schoolroom use.

It is so human a book that I don't see how belief in its divine authority can survive the reading of it.

We are stereotyped creatures, imitators and copiers of our past selves.

Of all the beautiful truths pertaining to the soul None is more gladdening or fruitful than to know You can regenerate and make yourself what you will.