(If you have to tell someone the same thing ten times, the idea probably wasn’t very well designed. No urban legend has to be repeated ten times.)

The Great Wall of China is the only man-made object that is visible from space. (The Wall is really long but not very wide. Think about it: If the Wall were visible, then any interstate highway would also be visible, and maybe a few Wal-Mart superstores as well.)

You use only 10 percent of your brain. (If this were true, it would certainly make brain damage a lot less worrisome.)

To strip an idea down to its core, we must be masters of exclusion. We must relentlessly prioritize.

The Golden Rule is the ultimate model of simplicity: a one-sentence statement so profound that an individual could spend a lifetime learning to follow it.

We can engage people’s curiosity over a long period of time by systematically “opening gaps” in their knowledge—and then filling those gaps.

In proverbs, abstract truths are often encoded in concrete language: “A bird in hand is worth two in the bush.” Speaking concretely is the only way to ensure that our idea will mean the same thing to everyone in our audience.

Sticky ideas have to carry their own credentials. We need ways to help people test our ideas for themselves—a “try before you buy” philosophy for the world of ideas.

Research shows that people are more likely to make a charitable gift to a single needy individual than to an entire impoverished region.

For instance, it’s difficult to get teenagers to quit smoking by instilling in them a fear of the consequences, but it’s easier to get them to quit by tapping into their resentment of the duplicity of Big Tobacco.

We are wired to feel things for people, not for abstractions. Sometimes the hard part is finding the right emotion to harness.

Research shows that mentally rehearsing a situation helps us perform better when we encounter that situation in the physical environment.

Similarly, hearing stories acts as a kind of mental flight simulator, preparing us to respond more quickly and effectively.

Once we know something, we find it hard to imagine what it was like not to know it. Our knowledge has “cursed” us. And it becomes difficult for us to share our knowledge with others, because we can’t readily re-create our listeners’ state of mind.

When people know the desired destination, they’re free to improvise, as needed, in arriving there.

“A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away.

Tversky and Shafir’s study shows us that uncertainty—even irrelevant uncertainty—can paralyze us.

Giving students two good alternatives to studying, rather than one, paradoxically makes them less likely to choose either.