Who would have thought that airports with their tedious lines and endless corridors could become so exciting? This week a new presidential order denying entry to people from several Middle Eastern countries caused consternation as immigration officers denied entry to some people with valid visas or green cards as well as all refugees. Fortunately for the country, several states protested and the courts have resisted the move and put a temporary halt on the order.

Prejudice against newcomers isn’t a new sentiment in the United States. Neither is prejudice against a particular religion that is seen as a threat to the country. From Colonial times on, many Americans have suspected that Roman Catholics with their “foreign” religion were a threat to the country.

The Irish immigrants who poured into the country from the 1840s on, were often the targets of discrimination by the press and clergy. Lyman Beecher, for instance, wrote that “The Catholic system is adverse to liberty, and the clergy to a great extent are dependent on foreigners opposed to the principles of our government, for patronage and support.”

One of the few writers who believed that the despised immigrants brought value to the country was Margaret Fuller. She praised the Irish immigrants for their generosity and family feeling and told her readers that they would be of great value to America. Fuller valued the contributions of other immigrants of the time too, including the Germans and Italians who could offer much to the country. My admiration for Margaret Fuller was what led me to write a biography of this brave woman.

Over the years, Americans learned that Catholics did not pose a threat to American values. They became a part of mainstream American life. But fearful people continue to fear. Today we are hearing echoes of Lyman Beecher as politicians talk about the threat of Muslims and of  Islamic thought. As of 2014, seven states had passed laws or ballot measures that banned Sharia law from influencing the courts. These states include Alabama, North Carolina, Arizona, Kansas, South Dakota and Tennessee. Currently the Montana legislature is arguing about the need for such a law.

President Trump appears to view the world as a threatening place and to fear that people professing a religion different from what he is used to must be dangerous. As any historian could tell him, people who are not descended from the handful of English settlers, have made this country great. Fear of anyone different from ourselves leads to stagnation, not greatness. Perhaps the president should listen to a brave woman like Marie Curie who said it well: Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.

And if President Trump wants to gain wisdom from the presidents who preceded him, he might pay attention to the words of one of our greatest leaders, Franklin Delano Roosevelt who famously announced that The only thing we have to fear is fear itself.