Our volitional habits depend, then, first, on what the stock of ideas is which we have; and, second, on the habitual coupling of the several ideas with action or inaction respectively.

When a thing is new, people say: ‘It is not true.’ Later, when its truth becomes obvious, they say: ‘It is not important.’ Finally, when its importance cannot be denied, they say: ‘Anyway, it is not new.

To know one thing thoroughly would be to know the universe.

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.

The baby, assailed by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion.

Language is the most imperfect and expensive means yet discovered for communicating thought.

In the matter of belief, we are all extreme conservatives.