An equally significant breakthrough resulting from Pasteur’s work was the idea of __21__ —killing bacteria on surgical instruments and other surfaces rather than introducing them into a patient’s body during surgery. After several years of hard work, Louis Pasteur’s long career __22__  in an enormously significant contribution to humankind—the vaccine. The concept of vaccination had existed at least since the end of the 18th century, when the English physician Edward Jenner noticed that people who had come down with a disease from cattle called cowpox were less likely to __23__ smallpox. Jenner began to introduce material from infected cows into people, with some positive results. Pasteur pursued Jenner’s idea and took one step forward by studying fowl cholera, a disease fatal to chickens. His experiments were interrupted by a summer vacation, and when Pasteur returned to the laboratory, he found that his cholera cultures were no longer lethal. In addition, he found that chickens __24__ this new weakened strain of the disease were not killed when they were later exposed to a lethal cholera culture. Pasteur’s work with weakened forms of diseases soon resulted in a vaccine against rabies. The vaccine famously saved the life of a shepherd boy named Joseph Meister when it __25__ after an attack by a rabid dog. Eventually, the knowledge that microscopic germs were the source of disease and infection led to vaccines to fight typhus, polio, measles, and other deadly diseases.

       Today’s robots must be precisely programmed to __26__ a car part or even help perform surgeries. But when it comes to__ 27__ an object they have not touched before, such as an egg, they often fail. Now, engineers have come up with a solution to overcome that limitation. Artificial Fingertips like TacTip could enable robots to __28__ objects of all shapes and sizes without such programming. The researchers are optimistic that TacTip will shrink. Cameras and microphones are getting smaller all the time, and 3D printing techniques are enabling thinner layers.
       They believe that such smaller devices might approximate human “feel” even more because they would be able to __29__ finer textures and thus be more dexterous. This research has explored how the skin’s nerve endings__30__ what they sense to get the fingers to catch a ball slipping through our fingers or pick up an origami crane without crushing it.

        Meaning “land between the rivers,” Mesopotamia is widely considered to be the cradle of civilization. It was here, in 5000 B.C., that people settled into an agricultural lifestyle by the mighty Tigris and Euphrates rivers. Because there was little rain, the people depended on these rivers for their survival. In particular, the Mesopotamians created canal channels to distribute the flood waters that flowed for a short duration each year to water their crops； the efficiency of their irrigation systems allowed their society to flourish in spite of little rainfall. This enables them to create the world’s first towns and cities. At the center of each town stood a temple complex with food stores, a treasury, and living spaces, all incorporated into the overall design. Over time, these towns evolved into city-states, eventually becoming an empire.

       In the beginning, there arose a need to keep reliable records of daily commodities traded； and out of this need, cuneiform－a wedge-shaped writing system－was invented. Later, this special writing system proved to be very versatile and quickly spread to uses other than documenting daily business transactions； for instance, the Sumerian scribed to record daily major life events and to write the first major literary work known to Western civilization. Perhaps the best known of Mesopotamia’s civilizations was Babylon. During the second millennia B.C., it rose from a regional capital to become the center of a kingdom that stretched across southern Iraq and beyond. Its king, Hammurabi, left his mark with a remarkable collection of laws. Hammurabi’s code defined the constraints of private property, as well as legal decisions for crimes, and family disputes.

       Although its architecture was eventually lost to the sands of time, Mesopotamia left a legacy of law, literature, and engineering, for modern civilizations to build on. In fact, much of what we know of that chapter in the region’s history has come from excavations of ruined cities, supplemented by recent discovery and written translations of Mesopotamia clay tablet texts.

        Most of us think of memes as silly things. Fads that fly around the internet and make us laugh for a moment before we forget them. Some memes last a while； some are all over the internet one day and are gone the next. First, let’s consider what a meme is. It’s an idea or a piece of culture—often a picture with some text—that can be passed from person to person. A meme is something that people repeat and imitate, but also adapt along the way. The meme’s power lies in the fact that it can spread so rapidly. There are several reasons for this. First of all, a meme provokes an instant reaction, usually laughter, sometimes shock or empathy, and that makes people want to share it. Second, a meme conveys information or feelings concisely. Instead of writing a long post about how bored you are, you can post a meme like this: It may make your friends laugh, but it also tells them how you’re feeling. Another reason why memes are powerful is that they allow for creativity and self-expression, because people don’t just share them, they also adapt them.

       Memes are a powerful way to spread ideas, so naturally, they’re also used for more serious messages. Images like a polar bear on a small iceberg have been used to comment on important issues, such as global warming. Now, does this particular polar bear’s situation have anything to do with global warming? Maybe. Maybe not. But if not, is it wrong for the image to be used this way if it gets your message across? What do you think? Some people argue that the way memes spread ideas so quickly can be a positive force for good, helping to raise awareness and build support for social movements, while others say that memes, at best, oversimplify complex situations, and at worst are a source of viral false information. At the very least, we need to think before we click that share button. What are we participating in, and why? Is it just for a quick laugh or a tug at the heart? Or is it something more powerful?

        In 1969, the Citizens Committee for the Conquest of Cancer, inspired by the success that year of the Apollo 11 space mission and propelled by the indomitable philanthropist Mary Lasker, conceived of a “moon shot” for cancer. That December, the group ran a full-page ad in The Washington Post and The New York Times: “Mr. Nixon: You can cure cancer.” At the time, a cure was perceived to be imminent. 

      President Richard Nixon’s grandiloquent response in his 1971 State of the Union address: “The time has come in America when the same kind of concentrated effort that split the atom and took man to the moon should be turned toward conquering this dread disease. Let us make a total national commitment to achieve this goal.”

      But the War on Cancer, as the moon shot was called, didn’t reach its goal. Partly, that was because “cure” was an erroneous target. Cancer is not one disease, but more than 200. “We talk about a ‘cure’ for cancer, but no one would ever use the term ‘cure’ for infectious disease—they would talk about a cure for AIDS or TB or malaria,” says the Harvard Chan School’s Giovannucci. “You have to think about these diseases one by one.” More fundamentally, the War on Cancer failed because it spent far too little on cancer prevention and cancer prevention research.

      There are many reasons why prevention research is unenticing to medical researchers. Most societies are reactive, rather than proactive, toward the problems they face. This explains why the final phases of the research on reactive treatment are usually simpler than the research on proactive prevention. Curing a patient with advanced disease is often more dramatic than preventing disease in a healthy person. And perhaps most conspicuously, treatments earn far higher profits than do new diagnostics or prevention measures.

       “The way I message this to lawmakers is that our well-being is a gift； we can’t take good health for granted, and prevention is a powerful way to protect that gift. When prevention works, you can enjoy the miracle of a perfectly normal, healthy day,” says Koh. “When I interact with lawmakers, I often ask about whether they have experienced the pain of losing a loved one when it could have been prevented. That usually humanizes the conversation and gives it relevance and immediacy.”