There are moments like the twin blasts in Boston on Monday, like the tragedy in Newtown, Conn, in December, like the shooting at Fort Hood in 2009 and even the 9/11 attacks themselves that send fear and worry throughout all of us. We wonder why bad people do such evil acts?

We see on Facebook that many people have posted a heartwarming answer to this question.

It comes from Fred Rogers, the kind host of the long-running PBS children’s show “Mr. Roger’s Neighborhood.” He sought to help children deal with the tragedies that get shown on television, heard over radio and read in the newspapers. Often, these children are too young to fully comprehend what happened.

He said: “My mother would say to me, ‘Look for the helpers. You will always find people who are helping.’ To this day, especially in times of disaster, I remember my mother’s words, and I am always comforted by realizing that there are still so many helpers — so many caring people in this world.”

We ask parents to speak with your children. They may not know what is going on, but they sure can sense worry and concern among adults. Many experts say it is good for children to know that, yes, it is OK for the kids to be sad or scared, too. Do not make them hide their feelings.

Mr. Rogers also said this: “For me, as for all children, the world could have come to seem a scary place to live. But I felt secure with my parents, and they let me know that we were safely together whenever I showed concern about the accounts of alarming events in the world.”