In the first study, Grant and his colleagues analyzed data from one of the five biggest pizza chains in the United States. They discovered that the weekly profits of the stores managed by extroverts were 16 percent higher than the profits of those led by introverts—but only when the employees were passive types who tended to do their job without exercising initiative. Introverted leaders had the exact opposite results. When they worked with employees who actively tried to improve work procedures, their stores outperformed those led by extroverts by more than 14 percent.

Introverts need to trust their gut and share their ideas as powerfully as they can.

The secret to life is to put yourself in the right lighting. For some, it's a Broadway spotlight; for others, a lamplit desk. Use your natural powers -- of persistence, concentration, and insight -- to do work you love and work that matters. Solve problems. make art, think deeply.

The purpose of school should be to prepare kids for the rest of their lives, but too often what kids need to be prepared for is surviving the school day itself.

The next time you see a person with a composed face and a soft voice, remember that inside her mind she might be solving an equation, composing a sonnet, designing a hat. She might, that is, be deploying the power of quiet.

Though shyness per se was unacceptable, reserve was a mark of good breeding.

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