Most people resist the idea of a true self-estimate, probably because they fear it might mean downgrading some of their beliefs about who they are and what they're capable of. As Goethe's maxim goes, it is a great failing to see yourself as more than you are. How could you really be considered self-aware if you refuse to consider your weaknesses? Don't fear self-assessment because you're worried you might have to admit some things about yourself. The second half of Goethe's maxim is important too. He states that it is equally damaging to value yourself at less than your true worth. We underestimate our capabilities just as much and just as dangerously as we overestimate other abilities. Cultivate the ability to judge yourself accurately and honestly. Look inward to discern what you're capable of and what it will take to unlock that potential.

If there is little or no diversity of views, and all scientists see, think, and question the world in a similar way, then they will not, as a community, be as objective as they maintain they are, or at least aspire to be. The solution is that there should be far greater diversity in the practice of science: in gender, ethnicity, and social and cultural backgrounds. Science works because it is carried out by people who pursue their curiosity about the natural world and test their and each other's ideas from as many varied perspectives and angles as possible. When science is done by a diverse group of people, and if consensus builds up about a particular area of scientific knowledge, then we can have more confidence in its objectivity and truth.

We tend to break up time into units, such as weeks, months, and seasons; in a series of studies among farmers in India and students in North America, psychologists found that if a deadline is on the other side of a break ― such as in the New Year ― we're more likely to see it as remote, and, as a result, be less ready to jump into action. What you need to do in that situation is find another way to think about the timeframe. For example, if it's November and the deadline is in January, it's better to tell yourself you have to get it done this winter rather than next year. The best approach is to view deadlines as a challenge that you have to meet within a period that's imminent. That way the stress is more manageable, and you have a better chance of starting ― and therefore finishing ― in good time.

The built-in capacity for smiling is proven by the remarkable observation that babies who are congenitally both deaf and blind, who have never seen a human face, also start to smile at around 2 months. However, smiling in blind babies eventually disappears if nothing is done to reinforce it. Without the right feedback, smiling dies out. But here's a fascinating fact: blind babies will continue to smile if they are cuddled, bounced, nudged, and tickled by an adult ― anything to let them know that they are not alone and that someone cares about them. This social feedback encourages the baby to continue smiling. In this way, early experience operates with our biology to establish social behaviors. In fact, you don't need the cases of blind babies to make the point. Babies with sight smile more at you when you look at them or, better still, smile back at them.

We collect stamps, coins, vintage cars even when they serve no practical purpose. The post office doesn't accept the old stamps, the banks don't take old coins, and the vintage cars are no longer allowed on the road. These are all side issues; the attraction is that they are in short supply. In one study, students were asked to arrange ten posters in order of attractiveness ― with the agreement that afterward they could keep one poster as a reward for their participation. Five minutes later, they were told that the poster with the third highest rating was no longer available. Then they were asked to judge all ten from scratch. The poster that was no longer available was suddenly classified as the most beautiful. In psychology, this phenomenon is called reactance: when we are deprived of an option, we suddenly deem it more attractive.

If we've invested in something that hasn't repaid us ― be it money in a failing venture, or time in an unhappy relationship ― we find it very difficult to walk away. This is the sunk cost fallacy. Our instinct is to continue investing money or time as we hope that our investment will prove to be worthwhile in the end. Giving up would mean acknowledging that we've wasted something we can't get back, and that thought is so painful that we prefer to avoid it if we can. The problem, of course, is that if something really is a bad bet, then staying with it simply increases the amount we lose. Rather than walk away from a bad five-year relationship, for example, we turn it into a bad 10-year relationship; rather than accept that we've lost a thousand dollars, we lay down another thousand and lose that too. In the end, by delaying the pain of admitting our problem, we only add to it. Sometimes we just have to cut our losses.

On our little world, light travels, for all practical purposes, instantaneously. If a lightbulb is glowing, then of course it's physically where we see it, shining away. We reach out our hand and touch it: It's there all right, and unpleasantly hot. If the filament fails, then the light goes out. We don't see it in the same place, glowing, illuminating the room years after the bulb breaks and it's removed from its socket. The very notion seems nonsensical. But if we're far enough away, an entire sun can go out and we'll continue to see it shining brightly; we won't learn of its death, it may be, for ages to come ― in fact, for how long it takes light, which travels fast but not infinitely fast, to cross the intervening vastness. The immense distances to the stars and the galaxies mean that we see everything in space in the past.

As the old joke goes: Software, free. User manual, $10,000. But it's no joke. A couple of high-profile companies make their living selling instruction and paid support for free software. The copy of code, being mere bits, is free. The lines of free code become valuable to you only through support and guidance. A lot of medical and genetic information will go this route in the coming decades. Right now getting a full copy of all your DNA is very expensive ($10,000), but soon it won't be. The price is dropping so fast, it will be $100 soon, and then the next year insurance companies will offer to sequence you for free. When a copy of your sequence costs nothing, the interpretation of what it means, what you can do about it, and how to use it ― the manual for your genes ― will be expensive.

Buying a television is current consumption. It makes us happy today but does nothing to make us richer tomorrow. Yes, money spent on a television keeps workers employed at the television factory. But if the same money were invested, it would create jobs somewhere else, say for scientists in a laboratory or workers on a construction site, while also making us richer in the long run. Think about college as an example. Sending students to college creates jobs for professors. Using the same money to buy fancy sports cars for high school graduates would create jobs for auto workers. The crucial difference between these scenarios is that a college education makes a young person more productive for the rest of his or her life; a sports car does not. Thus, college tuition is an investment; buying a sports car is consumption.

The Net differs from most of the mass media it replaces in an obvious and very important way: it's bidirectional. We can send messages through the network as well as receive them, which has made the system all the more useful. The ability to exchange information online, to upload as well as download, has turned the Net into a thoroughfare for business and commerce. With a few clicks, people can search virtual catalogues, place orders, track shipments, and update information in corporate databases. But the Net doesn't just connect us with businesses; it connects us with one another. It's a personal broadcasting medium as well as a commercial one. Millions of people use it to distribute their own digital creations, in the form of blogs, videos, photos, songs, and podcasts, as well as to critique, edit, or otherwise modify the creations of others.

Many things spark envy: ownership, status, health, youth, talent, popularity, beauty. It is often confused with jealousy because the physical reactions are identical. The difference: the subject of envy is a thing (status, money, health etc.). The subject of jealousy is the behaviour of a third person. Envy needs two people. Jealousy, on the other hand, requires three: Peter is jealous of Sam because the beautiful girl next door rings him instead. Paradoxically, with envy we direct resentments toward those who are most similar to us in age, career and residence. We don't envy businesspeople from the century before last. We don't envy millionaires on the other side of the globe. As a writer, I don't envy musicians, managers or dentists, but other writers. As a CEO you envy other, bigger CEOs. As a supermodel you envy more successful supermodels. Aristotle knew this: 'Potters envy potters.' ─> Jealousy involves three parties, focusing on the actions of a third person, whereas envy involves two individuals whose personal circumstances are most alike, with one person resenting the other.

We have biases that support our biases! If we're partial to one option ― perhaps because it's more memorable, or framed to minimize loss, or seemingly consistent with a promising pattern ― we tend to search for information that will justify choosing that option. On the one hand, it's sensible to make choices that we can defend with data and a list of reasons. On the other hand, if we're not careful, we're likely to conduct an imbalanced analysis, falling prey to a cluster of errors collectively known as confirmation biases. For example, nearly all companies include classic tell me about yourself job interviews as part of the hiring process, and many rely on these interviews alone to evaluate applicants. But it turns out that traditional interviews are actually one of the least useful tools for predicting an employee's future success. This is because interviewers often subconsciously make up their minds about interviewees based on their first few moments of interaction and spend the rest of the interview cherry-picking evidence and phrasing their questions to confirm that initial impression: I see here you left a good position at your previous job. You must be pretty ambitious, right? versus You must not have been very committed, huh? This means that interviewers can be prone to ignoring significant information that would clearly indicate whether this candidate was actually the best person to hire. More structured approaches, like obtaining samples of a candidate's work or asking how he would respond to difficult hypothetical situations, are dramatically better at assessing future success, with a nearly threefold advantage over traditional interviews.