"Over the years the unthinkable hasbecome thinkable and today we sense we are close to being able to alter humanheredity œ#)." These were the words of David Baltimore of the CaliforniaInstitute of Technology, on December 1st, when he opened a three-day meeting inWashington to discuss the morality and use of human gene editing. Dr Baltimoreis an old hand at these sorts of discussions, for he was also a participant inthe Asilomar conference, in 1975, which brought scientists together to discussa safe way of using the then-new tcchnology of recombinant DNA, and whoserecommendations influenced a generation of biotechnology researchers.

Four decades on, the need for a similarsort of chin-wag has arisen. The InternationalSummit on Human Gene Editing has been held by the national scientific academiesof three countries — America, Britain and China. They are particularlyconcerned about whether gene editing should be used to make heritable changesto the human germ line, something Dr Baltimore described as a deep andtroubling question. Like those of Asilomar, the conclusions of this meetingwill not be binding. But the hope is that, again like Asilomar, a mixture ofcommon sense and peer pressure will create a world in which scientists aretrusted to regulate themselves, rather than having politicians and civilservants do it for them. The meeting is being held against a backdrop of rapidscientific advance, Since 2012 research into a new, easy-to-use editing tool calledCRISPR-Cas9 has blossomed. This technique involves a piece of RNA (a chemicalmessenger, which can be used to recognise a target section of DNA) and anenzyme (酶)called a nuclease that can snip unwanted genes out and paste new ones in.

Public interest was aroused in April,when Chinese scientists announced they had edited genes in non-viable ( 无活力的) humanembryos, and again in November when British researchers said they hadsuccessfully treated a one-year-old girl who had leukaemia ( 白血病),using gene-edited T-cells. T-cells are part of the immune system that attack,among other things, tumour cells. The researchers altered T-cells from ahealthy donor to encourage them to recognise and kill the patient's cancer, tomake them immune to her leukaemia drug, and to ensure they did not attack herhealthy cells.

In another recent development, a firmcalled Edit as Medicine, which is based in Cambridge, Massachusetts, has saidit hopes, in 2017, to start human clinical trials of CRISPR-Cas9 as a treatmentfor a rare genetic form of blindness known as Leber congenital amaurosis (伯氏先天性黑蒙).Though other companies are already testing gene-editing therapies, these employolder, clunkier forms of the technology that seem likely to have lesscommercial potential. Moreover, researchers at the Broad Institute, also inCambridge, said this week that they had made changes to CRISPR-Cas9 whichgreatly reduce the rate of editing errors — one of the main obstacles to thetechnique's medical use.

On the subject of germ-line editing,Eric Lander, the Broad's head, told the meeting it would be useful only in rarecases and said it might be a good idea to "exercise caution? before makingpermanent changes to the gene pool. The need for caution is advice that mightalso be heeded by those pursuing work in animals other than people, and inplants — subjects not being covered by the summit.

    An elderly carpenter was ready to retire. He told his employer of his plans to leave the house building business and live a more leisurely life with his wife, enjoying his extended family. He would miss the pay check, but he needed to retire.

    The employer was sorry to see his good worker go and asked if he could build just one more house as a personal favor. The carpenter said yes, but in time it was easy to see that his heart was not in his work. He used shoddy materials to build the house. It was an unfortunate way to end his career.

    When the carpenter finished his work and the employer came to inspect the house, he handed the front-door key to the carpenter. “This is your house,” he said, “my gift to you.”

    What a shock! What a shame! If he had only known he was building his own house, he would have done it all so differently. Now he had to live in a home he hadn't built very well.

    It is the same with us. We build our lives in a distracted way, reacting rather than acting, willing to put up with less than the best. At important points, we don't give the job our best effort. Then with a shock we look at the situation we have created and find that we are now living in the house we have built. If we had realized that, we would have done it differently.

    Think of yourself as the carpenter. Think about your house. Each day you hammer a nail, place a board, or erect a wall, build wisely. It is the only life you ever build. Even if you live it for only one day more, that day deserves to be lived graciously and with dignity. The plague (牌匾) on the wall says, “Life is a do-it-yourself project.”

    Who could say it more clearly? Your life today is the result of your attitudes and choices in the past. Your life tomorrow will be the result of your attitudes and the choices you make today.

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    Guided Walking Week April 2016

    Dates: April 30^th-May 7^th 2016

    Location: Abdet, Costa Blanca

    A week of guided walking in the mountains around Abdet. Highlights include the climbing of Valencia's highest summit (Sierra de Aitana), traveling completely around the impressive Puig Campana, and several explorations in the Sierra de Aitana. Ancient trails lead through spectacular canyons(峡谷) to abandoned settlements situated high in the mountains. You will discover the snow trader routes which lead from the incredible snow holes high in the mountains down to the villages and towns on the coast. These years, golden eagles have made a return to this area, and you may also see other animals—wild goats, foxes, wild pigs and red squirrels.

    As part of the week you are invited to help clear some local walking paths. This involves clearing collapsed （坍塌的） walls and rocks, cutting back fallen trees. This is of course optional and is just for half a day, it's actually great fun!

Price:$499

Includes:

    Accommodation in the beautiful mountain village of Abdet

    All food-good home cooking

    Beer, wine, soft drinks

    Snacks and post walk treats

    Packed lunches & drinks(except café/bar visits)

    Expert guiding

    Photos/Videos of your days in the mountains

    Airport pick-up/return $25 each way(fly to Alicante)

    Single room supplement $75

    To book or get further information, please contact info@abdet.com.

    The health of millions could be at risk because supplies of medicinal plants are being used up. These plants are used to make traditional medicine, including drugs to fight cancer. “The loss of medicinal plants is a quiet disaster,” says Sara Oldfield, secretary general of the NGO Botanic Gardens Conservation International.

    Most people worldwide rely on herbal (药草制的) medicines which are got mostly from wild plants. But some 15,000 of the 50,000 medicinal species are under threat of dying out, according to report from the international conservation group Plantlife. Shortages have been reported in China, India, Kenya, Nepal, Tanzania and Uganda.

    Over-harvesting does the most harm, though pollution and competition from invasive species (入侵物种) and habitat destruction all contribute. Businessmen generally harvest medicinal plants, not caring about sustainability (可持续性),” the Plantlife report says, “damage is serious partly because they have no idea about it, but it is mainly because such collection is unorganized”. Medicinal trees at risk include the Himalayan yew (紫衫) and the African cherry, which are used to treat some cancers.

    The solution, says the report's author, Alan Hamilton, is to encourage local people to protect these plants. Ten projects studied by Plantlife in India, Pakistan, China, Nepal, Uganda and Kenya showed this method can succeed. In Uganda, the project has kept a sustainable supply of low-cost cancer treatments, and in China a public-run medicinal plant project has been created for the first time.”

    “Improving health, earning an income and keeping cultural traditions are important in encouraging people to protect medicinal plants,” says Hamilton, “You have to pay attention to what people are interested in.”

Ghillean Prance, the former director of the Royal Botanic Gardens at Kew in London, agrees that medicinal plants are in need of protection. “Not nearly enough is being done,” he told New Scientist. “We are destroying the very plants that are of most use to us.”

    Green is an important color in nature. It is the color of grass and the leaves on trees. It is also the color of most growing plants.

    Sometimes, the word "green" means young, fresh and growing. For example, a greenhorn is someone who has no experience. In the 15th century, a greenhorn was a young cow or an ox whose horns(角)had not yet developed. A century later, a greenhorn was a soldier who had no experience in war. By the 18th century, a greenhorn had the meaning it has today—a person who is new in a job.

    Someone who is good at growing plants is said to have a green thumb(大拇指). The expression comes from the early 20th century. A person with a green thumb can make plants grow quickly and well.

    Green is also the color used to describe the powerful feeling , jealousy(嫉妒). The green-eyed monster （怪物）is not a dangerous animal from outer space. It is an expression used about 400 years ago by the British writer William Shakespeare in his play "Othello". It describes the unpleasant feeling when someone has something he wants. For example, a young man may suffer from the green-eyed monster if you get a pay rise and he does not.

    In most places in the world, a green light means to move ahead. In everyday speech, a green light means agree to continue with a project.

    Bookstores are a traveller's best friends: they provide convenient shelter in bad weather, and they often host readings and other cultural events. Here is a look at the world's six greatest bookstores.

    Adrian Harrington—since 1971. Rare books; rare first editions; leather—bound sets and general antiques (古玩). Address: 64A Kensington Church Street, Kensington, London, England, U.K.

    Another Country— Kreuzberg, Berlin, Germany. Another Country is an English language second-hand bookshop which is mostly used as a library. They have about 20,000 books that you can buy or borrow. Some regular events are held at the shop, such as readings, cultural events, social evenings and film nights.

    Atlantis Books—Oia, Santorini, Greece. Atlantis Books is an independent bookshop on the island of Santorini, Greece, founded in 2004 by a group of friends from Cyprus, England, and the United States. Throughout the year it has hosted literary festivals, film screenings, book readings, and good old-fashioned dance parties.

    Bart's Books—Ojai, California, U. S. A. "The World's Greatest Outdoor Bookstore", a bookstore founded by Richard Bartinsdale in 1964. Shelves of books face the street, and regular customers are asked to drop coins into the door's coin box to pay for any books they take whenever the store is closed.

    10 Corso Como—Milan, Italy, Extensive selection of publication on art, architecture, design, graphics and fashion, along with a strong emphasis on photography. It was founded in 1990 in Milan, Italy, by Carla Sozzani.

    The Bookworm—A bookshop, library, bar, restaurant and event space, now with five locations in three cities in China—Beijing, Suzhou and Chengdu. The interconnecting rooms with floor-to-ceiling books on every wall are light and airy in summer, yet warm and comfortable in winter.