Schwartz's research suggests something important: we can stretch our personalities, but only up to a point. Our inborn temperaments influence us, regardless of the lives we lead. A sizeable part of who we are is ordained by our genes, by our brains, by our nervous systems. And yet the elasticity that Schwartz found in some of the high-reactive teens also suggests the converse: we have free will and can use it to shape our personalities.

Psychologists usually offer three explanations for the failure of group brainstorming. The first is social loafing: in a group, some individuals tend to sit back and let others do the work. The second is production blocking: only one person can talk or produce an idea at once, while the other group members are forced to sit passively. And the third is evaluation apprehension, meaning the fear of looking stupid in front of one's peers.

Solitude matters. And for some people it's the air they breathe.

Introverts often work more slowly and deliberately. They like to focus on one task at a time and can have mighty powers of concentration . They're relatively immune to the lures of wealth and fame.

Love is essential, gregariousness is optional.

Many people believe that introversion is about being antisocial, and that's really a misperception. Because actually it's just that introverts are differently social. So they would prefer to have a glass of wine with a close friend as opposed to going to a loud party full of strangers.

Solitude is one of our great superpowers... Solitude is the key to being able to make effective decisions and then having the courage of convictions to stand behind those decisions.