Ralph Emerson once said that the purpose of life is not to be happy, but to be useful, to be loving, to make some difference in he world. While we appreciate such words of wisdom, we rarely try to follow them in our lives.

Most people prefer to live a good life themselves, ignoring their responsibilities for the world. This narrow perception of a good life may provide short-term benefits, but is sure to lead to long-term harm and suffering. A good life based on comfort and luxury may eventually lead to more pain be-cause we spoil our health and even our character, principles, ideals, and relationships.

What then, is the secret of a good life? A good life is a process, not a state of being : a direction, not a destination. We have to earn a good life by first serving others without any expectation in return because their happiness is the very source of our own happiness. More importantly, we must know ourselves inside out. Only when we examine ourselves deeply can we discover our abilities and recognize our limitations, and then work accordingly to create a better world.

The first requirement for a good life is having a loving heart. When we do certain right things merely as a duty, we find our job so tiresome that we'll soon burn out. However, when we do that same job out of love, we not only enjoy what we do, but also do it with an effortless feeling.

However, love alone is insufficient to lead a good life. Love sometimes blinds us to the reality. Consequently, our good intentions may not lead to good results. To achieve desired outcome, those who want to do good to others also need to equip themselves with accurate world knowledge. False knowledge is more dangerous than ignorance. If love is the engine of a car knowledge is the steering wheel(方向盘). If the engine lacks power, th car can't move; if the driver loses control of the steering, a road accident probably occurs. Only with love in heart and the right knowledge in mind can we lead a good life.

With love and knowledge, we go all out to create a better world by doing good to others. When we see the impact of our good work on the world we give meaning to our life and earn lasting joy and happiness.

When you're bored, you might start playing with a ball or other objects. Such behavior is common in people. Other animals like it too—that's why a dog fetches a stick, or a cat bats at toys. Play is an enjoyable way to pass the time. A new study finds that it's not just mammals that like to play. Bumblebees（大黄蜂）do it too, making them the first insects known to play. 

In the study, Hiruni Samadi Galpayage Dona, an insect expert, did an experiment using 200 untrained bumblebees to see if they might play. Of those, 45 would be marked with a number when they emerged as adults. 

A pathway was set up from the bumblebees' nest to a feeding area. One side contained small wooden balls that rolled. The other side had the same number of balls, but they were stuck to the floor. Half balls on each side were colored balls. The rest were left unpainted. 

For three hours a day over 18 days, Galpayage Dona found bumblebees weren't so interested in the side where the balls didn't move, but they explored the side areas and interacted with the balls. Once they managed to roll a ball, they strongly preferred that side. They returned, climbing on the balls and rolling them around. She also found bumblebees preferred certain colors of balls. 

"There's something about the mobility that is more interesting for the bumblebees than just colored objects," Galpayage Dona says. In another experiment, she sometimes left the balls out overnight. "When I came in the next day, I would always find some bumblebees rolling the balls." As with mammals, the bumblebees who played the most were the younger ones. Their play tapered off as they got older. 

The scientists say it's not clear why the bumblebees roll the balls or whether they enjoy it. But the experiment raises important questions about how the insects' minds work and whether they have feelings. 

A joint research team recently have developed a new electronic skin that is similar to human skin in strength, durability and sensitivity. The skin or e-skin may play an important role in next-generation personalized medicine, soft robotics and artificial intelligence.

"The ideal e-skin will mimic(模仿)the many natural functions of human skin, such as sensing temperature and touch, accurately and in real time, " says leading researcher Yichen Cai. However, making suitably flexible electronics that can perform such delicate tasks while also used repeatedly is challenging, and each material involved must be carefully engineered.

Most e-skins are made by putting an active sensor on the surface that attaches to human skin. However, the connection between them is often too weak, which reduces the durability and sensitivity of the material; otherwise, if it is too strong, it won't be flexible enough, making it more likely to break the circuit.

"The landscape of skin electronics keeps shifting at a remarkable pace, " says Cai. "The discovery of 2D sensors has accelerated efforts to turn these quite thin but strong materials into functional, durable artificial skins. "

The new man-made skin built by the researchers could sense objects from 20 centimeters away. It could further make a quick response when touched in less than one tenth of a second. "It is a striking achievement for an e-skin to maintain toughness after repeated use," said Shen, "which mimics the softness and rapid recovery of human skin."

This type of e-skin could monitor a range of biological information, such as changes in blood pressure, which can be sensed from movements of arms and legs. This data can then be shared and stored on the cloud via Wi-Fi.

"One remaining problem to the widespread use of e-skins lies in mass production of high-resolution sensors, "adds group leader Vincent Tung, "however, the latest technology offers new promise."