I once had a friend who was diagnosed with terminal cancer, and the news that he might only live up to six months was a great shock to him, his family, and his friends. However, in spite of the serious illness, he was initially determined to look into all available treatments that might cure or extend his life. I think that when you find yourself in such situations, you tend to look up every possible way for hope of saving your life.

    As months went on and his health grew worse, I noticed an unexpected change in attitude that came over him. He had also been a happy person with a cheerful personality, but rather than give in to discouragement and self－pity, he took comfort in God and humanity. His talks focused on others rather than himself, and he spoke of the afterlife as something he was prepared for, believing that his concerned ancestors, including his mother and father, were there waiting for him.

    During the last few months, weeks, and days of his life, he was kindly cared for by family, friends, his loving wife, who looked after both his physical and emotional needs, and workers from a local hospice (安养院) came to the home to regulate his medication and provide any other needed support. He didn't complain about his fate, and he willingly allowed others to serve him.

    Indeed, one might think why God allows death and suffering in our world, but for me, such experiences taught me to value family more and kindness for others. You often can't learn these important attributes in the lap of luxury, and perhaps, such an experience is the greatest and final gift the illness can give those left behind.

    Crown shyness (树冠羞避) is a mysterious natural phenomenon in which the crowns of some tree species do not touch each other, but get separated by a gap clearly seen from ground level. The effect usually occurs between trees of the same species, but has also been observed between trees of different species.

    There are many theories going around, most of which make sense, but no one has been able to prove without the shadow of a doubt why some trees avoid touching each other.

    In his 1955 book Growth Habits of the Eucalypts, Australian forester M. R. Jacobs writes that the growing tips of the trees are sensitive to abrasion (擦伤), which results in crown shyness phenomenon. This theory was also supported by Dr. Miguel Franco. Some experiments have shown that if trees displaying crown shyness are artificially prevented from swaying (摇摆)in the wind and touching each other, they gradually fill up the gaps between them.

    But while the above theory is arguably the most widespread, it's certainly not the only one. Some scientists have suggested that crown shyness is a mechanism to stop the spreading of leaf-eating insects. The gaps mean pests wouldn't be able to reach other trees, so they are the tree's natural defense method.

    One Malaysian scholar studied many trees, but found no traces of abrasions, despite their clear crown shyness. Instead, he suggests that the growing tips of the trees were sensitive to light levels and stopped growing when they got too close to other trees. Plants are able to sense how close they are to other plants and in order to get more light, they give off some chemical to stop other trees from growing too close.

    Whatever the reason, one thing is for sure, plants are more intelligent than people.

    Until late in the 20th century, most Americans spent time with people of generations. Now mid-aged Americans may not keep in touch with old people until they are old themselves. That's because we group people by age. We put our three-year-olds together in day-care center, our 13-year-olds in school and sports activities, and our 80-year-olds in senior-citizen homes. Why?

    We live away from the old for many reasons: Different generations have different lifestyles. Besides, young people sometimes avoid the old to get rid of fears for aging and dying. It is much harder to watch someone we love disappear before our eyes. Sometimes it's so hard that we stay away from the people who need us most.

    Fortunately, some of us have found our way to the old. And we have discovered that they often save the young. A reporter moved her family onto a block filled with old people. At first her children were disappointed. But the reporter baked banana bread for the neighbors and had her children deliver it and visit. Soon the children had many new friends, with whom they shared food, stories and projects. “My children have never been less lonely,” the reporter said.

    The young, in turn, save the old. Once I was in a rest home when a visitor showed up with a baby. She was immediately surrounded. People who hadn't gotten out of bed in a week suddenly were ringing for a wheelchair. Even those who had seemed asleep wake up to watch the child. Babies have an astonishing power to comfort and cure.

    Grandparents are a special case. They give grandchildren a feeling of security and continuity. As my husband put it, “my grandparents gave me a deep sense that things would turn out right in the end.”

    Grandchildren speak of attention they don't get from worried parents. “My parents were always telling me to hurry up, and my grandparents told me to slow down,” one friend said. A teacher told me she can tell which pupils have relationships with grandparents: they are quieter, calmer, more trusting.

    Eating chips, chocolates and cakes may damage a child's intelligence, according to researchers at Bristol University. Their study suggests a link between diet high in processed(加工的) food and a slightly lower IQ. Writing in the journal of Epidemiology and Community health, they suggest poor nutrition may affect brain development.

    The eating habits of 3,966 children taking part in the Avon Longitudinal Study of Parents and Children were recorded at the ages of three, four, seven and eight and a half. The researchers said three types of diet appeared: processed diet which was high in fat, sugar and fast food, traditional diet of meat, potatoes and vegetables, and healthy diet of salads, fruit and fish. The children all took IQ tests when they were eight and a half.

    The researchers found a link between IQ and diet, even after taking into consideration other factors such as the mother's level of education and social class. Diet high in processed food at the age of three was linked to a slightly lower IQ at the age of eight and a half, suggesting early eating habits have a long-term influence. Dr Pauline Emmett, who carried out the study at Bristol University, said, “Brain development is much faster in early life, and it's when it does most of its growing.”

    Although the relationship between diet and IQ was very strong, the influence was quite small. Processed food was linked with IQs only a few points lower. Experts in the field said the results had shown common sense was right. Fiona Ford, spokesperson for the British Dietetic Association, said, “It's well worth looking at the long-term influence of diet, for everyone's familiar with the short term. The research agrees with the type of advice we already know, but that's not always enough. Sometimes a society has to help a person change; we need to educate more young parents about healthy eating.”

    The words “protect animals” appear everywhere in books and on screens because some animals are in danger of dying out. But sometimes the reality can be a little different from what people read or watch.

    Florida, US, has held its first bear hunt since 1994. The local government gave people nearly 4,000 permits to kill black bears. And more than 200 were killed on Oct 24.

    Animal protection groups protested this decision. But local officials explained that the black bear population had grown to 3,500 and become a menace to local people. In the past two years, bears have hurt at least four people in Florida.

    This brings an old question back into the spotlight – which is more important, protecting animals or protecting people's interests?

    This question is asked in other countries too. In Switzerland, a wolf was sentenced to death by the Swiss government months ago. This is because the wolf killed 38 sheep and local people lost a lot of money. Days ago in China, three old men were arrested for killing a serow(鬣羚), a protected species. But they insisted they didn't know about this and killed the animal because it ruined their crops.

    However, these stories don't always mean that animal protection stops due to human interests, especially involving economic development. A man named Zhou Weisen set up a wild animal base in Guilin, Guangxi. He saved over 170 tigers and 300 bears. But his base also offered jobs to local people.

    “There may never be a standard answer to the question of whether we should give more attention to the environment or human development,” said Robert May, a British biologist at Oxford University. “But we shouldn't push either one to the side, as the future is hanging in the balance.

Intelligence is traditionally viewed as the ability to think and learn. Yet in a complex world, there's another set of cognitive (认知的) skills that might matter more: the ability to rethink. Therefore, my aim in this book is to explore how rethinking happens by seeking out the most convincing evidence and some of the world's most skilled rethinkers.

The first section focuses on opening our own minds. You'll find out why a forward-thinking businessman got trapped in the past, how a Nobel Prize-winning scientist welcomes the joy of being wrong, how the world's best forecasters update their views, and how an Oscar-winning filmmaker has productive fights.

The second section examines how we can encourage other people to think again. You'll learn how an international debate champion wins arguments and an African-American musician persuades people to abandon discrimination (歧视). You'll discover how a special kind of listening helped an officer convince the opposing side to join in peace talks. And if you're a Yankees fan, I'm going to see if I can convince you to root for the Red Sox.

The third section is about how we can create communities of lifelong learners. In social life, a lab that specializes in difficult conversations will cast light on how we can communicate better about debated issues like climate change. In schools, you'll find out how educators teach kids to think again by treating classrooms like museums, and approaching projects like rewriting time-honored textbooks. I close by examining the importance of reconsidering our best-laid plans.

This book is an invitation to let go of knowledge and opinions that are no longer serving you well, and to establish your sense of self in flexibility rather than consistency. If you can master the art of rethinking, I believe you'll be better positioned for success at work and happiness in life. Thinking again can help you generate new solutions to old problems and revisit old solutions to new problems. It's a path to learning more from the people around you and living with fewer regrets.