You may be familiar with the following famous people, but have you heard of their graduation speeches, in which they either share their unforgotten experiences or give you some great inspiration(启迪).

    Michael Dell, University of Texas at Austin

    And now you've accomplished something great and important here, and it's time for you to move on to what's next. And you must not let anything prevent you from taking those first steps. ... You must also commit to the adventure. Just have faith in the skills and the knowledge you've been blessed (赐予)with and go.

    J.K. Rowling, Harvard University

    Half my lifetime ago ,I was striking an uneasy balance between my ambition and the expectation from my parents who were not rich...But what I feared most for myself at your age was not poverty(贫穷), but failure. The fact that you are graduating from Harvard suggests that you know little about failure, you might be driven by a fear of failure quite as much as a desire for success.

    Steve Jobs, Stanford University

    Sometimes life's going to hit you in the head with a brick. Don't lose faith...Your work is going to fill a large part of your life, and the only way to be truly satisfied is to do what you believe is great work, and the only way to do great work is to love what you do. If you haven't found it yet, keep looking, and don't settle.

    Bill Gates, Harvard University

    We need as many people as possible to have access to the advanced technology to lead to a revolution in what human beings can do for one another. They are making it possible not just for national governments, but for universities ,smaller organizations, and even individuals to see problems, see approaches and deal with the world's inequities（不公平）like hunger, poverty, and so on.

    There might be as many as 10 million species of complex life on this planet today —— a huge number. But add up all of the complex species that ever lived and some biologists think the grand total would be about five billion. The estimate leads to an astonishing conclusion: a staggering 99% of species are not around any more. They have been driven to extinction.

    More species are joining the ranks of the extinct every year. Many scientists believe we are living through an episode of remarkably rapid extinction, on a scale that has been seen only five times in the last half a billion years.

    They call this current episode the sixth mass extinction —— a large, global decline in a wide variety of species over a relatively short period of time. And they tend to agree that humans are the main cause.

    Over-hunting, overfishing, and human-driven habitat loss are pushing many species to the brink. In fact, we have changed the planet so much that some geologists are now suggesting that we have entered a new phase in Earth's history; an epoch they call the ＂Anthropocene＂. By 2100, it is expected that humans will have caused the extinction of up to half of the world's current species.

    Because we are living through this extinction, it is relatively easy for us to study the driving forces behind it. But how do we determine what caused other mass die-offs that happened long ago? To do so we have to look at what archaeologists, palaeontologists, geologists and other scientists have concluded from the evidence they have gathered.

    The trouble is, those scientists do not always agree with one another —— even about the most recent extinction event. As well as the five-or six- mass extinctions, there have also been many smaller extinctions.

    One of these mini extinction events happened towards the end of the Pleistocene, a few tens of thousands of years ago. It is sometimes called the ＂megafaunal＂ extinction because many of the species it claimed were particularly large animals, weighing more than 97lb (44kg). However, its cause remains a debate amongst scientists.

    In his research work, Philosophical Investigations（哲学调查）, Ludwig Wittgenstein tries to clarify（澄清）some of the problems in people's thinking about how the mind works.

    Imagine, he says, that everyone has a small box in which they keep a beetle（甲壳虫）. No one is allowed to look in anyone else's box, only in their own. Over time, people talk about what is in their boxes and the word “beetle” comes to stand for what is in everyone's box. Through this example, Wittgenstein point out that the beetle is very much like an individual's（个体的）mind; no one can know exactly what it is like to be another person or experience things from another's point of view—look in someone else's “box”—but it is general considered that the mental working of another person's mind is very similar to that of our own. However, it does not really matter—he argues—what is in the box or whether everyone indeed has a beetle, since there is no way of checking or comparing. In a sense, the word “beetle” simply means “what is in the box”. From this point of view, the mind is simply “what is in the box”, or rather “what is in your head”.

    Wittgenstein considers language to have meaning because of public usage. In other words, when we talk of having a mind—or a beetle—we are using a term that we have learned through conversation. The concept might be perceived（感知）differently in each of our minds, so the word “mind” cannot be used to refer specifically to some entity（本质）outside of our own conception（概念）, since we cannot see into other people's boxes.

    Many languages are disappearing and languages such as English, Spanish and Chinese are increasingly taking over. Yet Maori promises to have a rosy future given that New Zealanders are showing great enthusiasm for speaking this local language.

    A "Maori renaissance (复兴)" blossomed in the 1970s as language activists championed their cause and Maori fought for greater political power. But until 2013, just 3.7 percent of New Zealanders spoke the language fluently, and many predicted it would soon die out. Now New Zealand's government is erasing prejudice and struggling to increase the percent of population who can speak basic Maori by 2040 to 20. Prime Minister Jacinda Ardem said last month that her newborn daughter would learn both Maori and English. "It's an official language, so why should we dismiss its universal availability and its much more common use?" said Ms. Ardem, adding that she also planned to study the language. Grassroots are also spreading it by word of mouth Answering the phone with the greeting "kiaora" (hello) or ending an email withunga mihi' (thanks) has become a fashion. Maori is gradually becoming part of New Zealand's mainstream popular culture.

    Ajit Kumar Samah, a famous professor in Auckland University, published a book—Coniagious: why Maori catches on, where he introduces readers to the popularity of Maori and expresses his great anxiety for the lack of teachers who have the competence to teach the Maori language.

    People are not on the same wavelength, however. Suggestions on officially replacing English-language place names with traditional Maori ones have been rejected. So when a police car was designed using Maori, it was condemned by some as ridiculous because of the higher Maori rates of arrest and imprisonment.

 Last week, my younger brother visited me for five days. To ensure I could spend as much time with him as possible, I worked extra hard during the weekend before he arrived.

 It amazed me how much I could accomplish when I had a strong motivation to be efficient.

 During the week, I put in a couple of hours in the mornings to handle pressing issues and then spent the afternoons and evenings going out with him. Once again, I was surprised to realize just how much free time was available to me if I consciously chose to be more effective while working.

 This made me think of Parkinson's Law: Work expands to fill the time available for its completion.

 I realized then that I'd given myself more time than necessary for work, and as a result, I ended up spending a lot of time delaying needlessly and entertaining myself online.

 How might things change for me, I wondered, if I chose to commit to more social and recreational activities, made them priorities and was motivated to finish work quicker?

 I realize not everyone has flexible work schedules, but I believe we could all create more time for ourselves if we were motivated to cut out the choices that don't match our strongest desires and intentions. Maybe it's being absent-minded in front of the TV or searching the web.

 I believe what English musician John Lennon said is true: Time that you enjoyed wasting was not wasted.1 don't think there's anything wrong with using technology if we've consciously chosen to do it.

 However, we owe it to ourselves to get out in the world and explore different possibilities—to be playful, curious, engaged and just to be.

 Perhaps it would be easier to do that if we asked ourselves: How can I be more effective? Can I minimize what I am currently doing? How can I start using the time I've created in a way that will excite and inspire me?

Much of Earth is unexplored. An ocean census (普查) hopes to change that.

"Earth" has always been an odd choice of name for the third planet from the Sun. After all, two-thirds of its surface is covered not by earth at all, but by oceans of water.

Because humans are land animals, most of the Earth remains under-explored. Marine (海洋的) biologists think the oceans might host more than 2 million species of marine animals, of which they have so far identified perhaps a tenth.

A new initiative hopes to change this. Launched in London on April 27th, Ocean Census aims to discover 100, 000 new species of marine animal over the coming decade. It is backed by Nekton, a British marine-research institute, and the Nippon foundation, Japan's biggest charitable foundation. Its first ship, the Norwegian icebreaker Kronprins Haakon, set sail on April 29th, bound for the Barents Sea.

The initiative is happening for two reasons. One is that the longer scientists wait, the less there will be to identify. Climate change is heating the oceans, as well as making them more acidic (酸的) as carbon dioxide dissolves goes into the water. Already around half the world's coral reefs (珊瑚)—thought to be home to around 25% of all ocean species—have been lost. Oliver Steeds, Nekton's founder, says that one of Ocean Census's priorities will be identifying species thought to be in the greatest danger from climate change. The second reason is technological. Marine biologist s find about 2, 000 new species a year, a rate hardly changed since Darwin's day. Ocean Census is betting it can go faster.

Exactly what the new effort might turn up is impossible to predict. But history suggests it will be fruitful. Half a century ago scientists discovered hot vents (喷口) on the sea bed. These days, such vents are one possible candidate for the origin of all life on Earth. There are more practical benefits, too. Many drugs, for example, come originally from biological substance. An ocean full of unidentified life will almost certainly prove a rich mine from which to mine more.