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Here is an astonishing and significant fact: Mental work alone can't make us tired. It sounds absurd. But years ago, scientists tried to find out how long the human brain could labor without reaching a stage of fatigue (tiredness). To the amazement of these scientists, they discovered that blood passing through the brain, when it is active, shows no fatigue at all! If we took a drop of blood from a day laborer, we would find it full of fatigue toxins (毒素) and fatigue products. But if we took blood from the brain of an Albert Einstein, it would show no fatigue toxins at the end of the day.

So far as the brain is concerned, it can work as well and swiftly at the end of eight or even twelve hours of effort as at the beginning. The brain is totally tireless. So what makes us tired?   

Some scientists declare that most of our fatigue comes from our mental and emotional attitudes. One of England's most outstanding scientists, J.A. Hadfield, says, “The greater part of the fatigue from which we suffer is of mental origin. In fact, fatigue of purely physical origin is rare.” Dr. Brill, a famous American scientist, goes even further. He declares, “One hundred percent of the fatigue of sitting worker in good health is due to emotional problems.”

    What kinds of emotions make sitting workers tired? Joy? Satisfaction? No! A feeling of being bored, anger, anxiety, tenseness, worry, a feeling of not being appreciated—those are the emotions that tire sitting workers. Hard work by itself seldom causes fatigue. We get tired because our emotions produce nervousness in the body.

    You carry a 1.3 kg mass of fatty material in your head that controls everything you will ever do. This fantastic control center lets you think, learn, create, and feel emotions. It also controls everything your body does. What is this amazing machine? It's your brain — a structure so amazing that the famous scientist James Watson called it ＂the most complex thing we have yet discovered in our universe＂.

    Imagine your kitten jumped onto the kitchen counter, and was about to step onto a hot stove. You would have only seconds to act. In situations like this, your brain reads the signals from your eyes and quickly calculates when, where and at what speed you need to run to save her. Then it tells your muscles to move. No computer can match your brain's great ability to download, process, and react to the flood of information from your eyes, ears and other sensory organs.

    If a bee lands on your foot, sensory neurons(神经元) in your skin send this information to your brain at a speed of more than 240 kilometers per hour. Your brain then uses motor neurons to send a message back to your foot: Shake the bee off quickly! Motor neurons can send this information at more than 320 kilometers per hour!

    Your brain contains about 100 billion tiny cells: neurons — it would take you more than 3,000 years if you tried to count them all. Whenever you dream, laugh, think, see or move, tiny chemical and electrical signals are racing between these neurons along billions of tiny neuron pathways. Believe it or not, the activity in your brain never stops. Countless messages fly around inside it every second, like a super-fast game of table tennis. Your neurons create and send more messages than all the phones in the entire world. And although a single neuron generates only a tiny amount of electricity, all your neurons together can generate enough electricity to power a light bulb.

    Here are some recommendations for tourists to choose from.

    Banff, Canada

    Banff, located in the Rockies, has a view of tall mountains, deep valleys and lakes, making it the first town to become part of the country's national parks. Tourists can enjoy its beauty by hiking, horse riding and boat trips. Banff was founded in 1883 while a railroad was in construction. It was the water springs that drew the engineers' attention to the place as a settlement. With such a fantastic view, it's no surprise that Banff hosts a number of cultural festivals.

    Lisbon, Portugal

    Lisbon is the capital of Portugal, with the warmest winters of any major European city.

    Belem Tower and Jeronimos Monastery are listed as UNESCO World Heritage Sites. The former was built in the 16^th century as a symbol of Portugal's Extraordinary Age and the latter is one of the greatest examples of the Portuguese late-Gothic style of architecture. The Lisbon Oceanaium is among Europe's finest aquariums. The Museum Calouste Gulbenkian is among the best museums in Europe containing priceless artworks covering 4000 years from ancient Egyptian times to the late 20^th century.

    Portland, US

    Portland is frequently recognized as one of the world's most environmentally-friendly cities because of its well-built pavements, large community of cyclists and convenient public transportation. Us climate is ideal for growing roses and it's called the “City of Roses”. Besides, the seaport is also known as a city of beer: it has the largest number of beer breweries（啤酒厂）of any city in the world. Today's Portland is better known for its music. It's called “the capital of karaoke” and “one of the most exciting music scenes” in the US.

    Bordeaux, France

    Bordeaux attracts tourists with its rich cultural heritage, especially its wealth of architectural treasures. Besides the Cathedral of Saint Andrew dating back to 12^th century, the Basilica of Saint Michael is another one of the city's UNESCO World Heritage Sites. It took 200 years to build from 14^th to 16^th centuries. Other significant buildings include the Grand Theater built in 1780 in the new Classical style and the Stone Bridge built in 1821.

    A bright yellow “M” tells you that it's a McDonald's restaurant; we also associate the cheerful theme tune “I'm Lovin' It” with the famous US fast food.

A brand's music has a similar effect on its customers as its logo. “It appeals directly to the heart, where consumers' decisions are really made,” wrote Marketing Week.

This is probably why companies from around the world have recently focused more on building a “sonic (声音的) identity”.

    An example is the software company Tencent QQ. Since 2014, this Chinese company has been trying to trademark (申请商标权) its “Di-Di-Di-Di-Di-Di” notification sound. The trademark was finally approved on Nov 15, which means that Tencent's “Di-Di-Di-Di-Di-Di” notification sound is now protected by law and can only be used by QQ.

    Sound and music can also help tell stories. In Game of Thrones (《权力的游戏》) there are so many characters that it is difficult to memorize them all. So, they wrote melodies (旋律) specific to each family. The result is that characters do not only look familiar, but sound familiar too.

    “I think a huge reason why sound inspires action is that, on an unconscious level, we are always listening,” Lauren Nagel, executive creative director at Pandora Media, told GeoMarketing. “You can close your eyes, but you can't shut your ears.”

    Next autumn when you see wild geese heading south for the winter flying in a V formation you might think about what scientists have discovered as to why they fly that way.

    As each bird flaps(拍打) its wings, it creates an uplift(升力) for the bird immediately following. By flying in V formation the whole group adds at least 71% greater flying range(航程) than if each bird flies on its own.

    People who share a common direction and sense of community can get where they are going more quickly and easily because they are traveling on the push of one another. When a wild goose falls out of the formation, it suddenly feels the drag and resistance(阻力) of trying to go alone and quickly tries to get back into the formation to take advantage of the lifting power of the bird in front. When the head goose gets tired, it flies back into the formation and another goose flies to the front. It is wise to take turns doing difficult jobs whether it be people or wild geese flying south.

    Wild geese honk(发出雁叫声) from behind to inspire those up front to keep up their speed. When a wild goose gets sick or wounded by gunshots, and falls out of the formation, two other geese will fall out with that goose and follow it down to lend help and protection. They will stay with the fallen goose until it is able to fly or until it dies, and only then will they go on with their own or with another formation to catch up with their group.

    Notre-Dame de Paris, a cathedral church in Paris, is the most famous of the Gothic cathedrals of the Middle Ages. For the French, it represents something immortal, ever- present and unchanging, like a mountain. Built over almost two centuries, the Notre-Dame is, as President Emmanuel Macron said, "where the French lived all their great moments". Soldiers prayed here before leaving for the Crusades; Napoleon Bonaparte was crowned here; it survived the French Revolution, two World Wars and the Nazi occupation. It is where men bend their knees to profess love and thousands of tourists take photos every day.

    A fire, whose cause was not identified yet, engulfed(吞没), on April 15th, the cathedral's upper structure. More than 400 firefighters took part in the 15-hour battle to control the blaze(火苗) that triggered sorrow over the globe. The extent of the damage is still unknown, but the fire destroyed much of the gothic cathedral's wood-timbered roof and spire(塔尖). The cathedral will certainly be restored (the French government promises), but the sight of flames bringing down the spire moved the world in a manner far exceeding its religious significance.

    French Culture Minister Franck Riester on Thursday said the government would draw all the consequences from the huge flames that destroyed the centuries-old Notre Dame Cathedral, adding measures to protect the national heritage were on the table. "Staff from the fire department, the culture ministry and the city town hall rushed to the Cathedral, when the fire started, to protect the main artworks that were inside. The artworks, which include relics such as the Christ's crown of thorns and French king Saint-Louis's 13th century tunic, were first moved to the city town hall and will now be transferred to the nearby Louvre Museum ." the minister told Le Parisian newspaper in an interview without giving details on the possible measures.