3 . Those with closed minds refused to consider any contradictory facts, and they proceed with their planned course of action, full speed ahead, with their “minds made up” and tightly shut. As an illustration, consider the situation in 1986, prior to the space shuttle Challenger’s disatrous launch that killed all seven astronauts aboard, there was a heated telephone debate between two engineers from the company that produced the shuttle booster rockets and the top officials of NASA (the federal government’s space agency). The engineers insisted that the flight was too risky because of freezing temperature at the Florida launch site. They explained that some of the seals on the fuel tanks were not designed to withstand such low temperatures and might leak under pressure, thus endangering the craft and crew.

Despite the pleas to stop the flight, officials at NASA overruled the engineers, who were best qualified to make judgments about the complex technical problems of space flight. What caused the officials to ignore the engineers? Several flights had already been postponed, and it would not look good to postpone another. It would be bad public relations to disappoint the crowds of people and news reporters waiting for the launch. Top government officials were ready to appear on the national television and take the credit for another safe flight. As a result, with their minds absolutely closed to the facts presented by the engineers, NASA officials ordered the Challenger to take off. Seventy-three seconds later, the spacecraft was enveloped in flame.

Incredibly, seventeen years later, the lesson of the Challenger disaster was repeated. In 2003, the space shuttle Columbia broke apart while re-entering the earth’s atmosphere, killing another crew of seven. During the shuttle’s liftoff, a piece of foam insulation(泡沫隔热材料) had broken off, hitting the shuttle's wing at five hundred miles per hour. Lower-level engineers at NASA begged for photographs of the Columbia in orbit, which might have shown the extent of the damage, but their closed-minded superiors ignored their requests. It was the damage caused by the 1.7 pound chunk of insulation that doomed the Columbia.

There is no virtue in ignoring contradictory facts and “sticking to your guns” when the course taken shows all the signs of being the wrong one. Closed minds are especially noticeable in political campaigns and debates. Many people line up to support one candidate or another and won’t listen to any facts presented by the opposing candidate.

All those with an open mind say is this: “I don’t know everything, so I’d better keep my mind, eyes, and ears open to any new facts that may come along.” The world would be a much better and safer place if everyone had this attitude.

4 . Time flies, but the tracks of time remain in books and museums. This is what made a recent tragedy in Brazil even more terrible.

On Sept.2, a big fire ripped through the National Museum of Brazil. “ Two hundred years of work, research and knowledge were lost, ” Brazilian President Michel Temer wrote on Twitter after the fire. “It's a sad day for all Brazilians.”

Most of the 20 million pieces of history are believed to have been destroyed. Only as little as 10 percent of the collection may have survived, Time reported. Among all the items, there were Egyptian mummies, the bones of uniquely Brazilian creatures such as the long－necked dinosaur Maxakalisaurus, and an 11,500－year－old skull called Luzia, which was considered one of South America's oldest human fossils.

Besides these, Brazil's indigenous(本土的，土著的) knowledge also suffered. The museum housed world－famous collections of indigenous objects, as well as many audio recordings of local languages from all over Brazil. Some of these recordings, now lost, were of languages that are no longer spoken.

“The tragedy this Sunday is a sort of national suicide, a crime against our past and future generations,” Bernard Mello Franco, one of Brazil's best－known columnists, wrote on the O Globo newspaper site.

The cause of the fire is still unknown, as BBC News reported on Sept. 3. After the fire burned out, crowds protested outside the museum to show their anger at the loss of the irreplaceable items of historical value.

According to Emilio Bruna, an ecologist at the University of Florida, museums are living, breathing stores of who we are and where we've come from, and the world around us.

Just as underwater grass floats on the surface if it loses its roots, a nation is lost without its memories. The fire at the National Museum of Brazil teaches the world an important lesson: We should never neglect history.