Bill Littlefield reflects on Monday's trajedy at the Boston Marathon. (Julio Cortez/AP)

U.S. flags hang from a barricade as Massachusetts National Guard members keep watch Tuesday near the site of the Boston Marathon bombings. Monday’s blasts left three dead. (Julio Cortez/AP)

U.S. flags hang from a barricade as Massachusetts National Guard members keep watch of Boylston Street near the site where a day earlier explosions near the Boston Marathon finish line killed three and injured dozens.

The meaning of the bombings at the Boston Marathon is that one moment three people were smiling and cheering and looking for their relatives and friends among the throng of runners, and the next moment they were dead.

The meaning of the bombings is that one moment scores of other people were standing beside the road, excited to be witnessing one of Boston’s signature events, and the next moment they were on the ground and injured.

The meaning of the bombings in Boston is that many people who’d planned to make a day of watching the marathon had their lives changed forever by the explosions. Some of them will mourn the loss of people they loved, and some will undergo long and painful rehabilitations. Some of them will carry for the rest of their lives the images we normally associate with war.

It is comforting to reassure ourselves that in the moments after the bombs went off, numbers of brave and resourceful people came to the aid of the injured. Their quick action saved lives, and their courage provided us with heroes, and with hope. Others rushed to donate blood, and neighbors and friends have offered what they can, and we who live in and around Boston have heard from friends and relatives concerned for us and for our city.

It is comforting, too, to think that the science of those charged with piecing together what was left of the bombs might enable the authorities to identify those responsible for causing the deaths and the injuries, and for creating the shock and confusion and pain and anger that so many people in Boston and elsewhere have experienced since Monday’s awful events.

And it is comforting, although not surprising, to know that Sunday’s London Marathon will go on, and there is comfort, too, in all the assertions that the Boston Marathon will endure as an institution.

We are – we must be – grateful for all that comforts the families forever diminished by the bombing and those injured in the explosions, just as we are grateful for and encouraged by the actions of those who courageously offer aid to those damaged by violence wherever it is perpetrated by one of us against another on whatever pretense.

But the meaning of these terrible and terrifying events is in the human damage done, and in the compassion we can feel, and in the hope that there can be no cruelty so extreme that it will render us numb and crush our capacity to feel that compassion.