Bill Greene, Associated Press
In this Monday, April 15, 2013 photo, former New England Patriots player Joe Andruzzi carries a woman from the scene of two blasts at the finish line of the Boston Marathon on Exeter Street in Boston.

As I write this, federal and state law enforcement investigators are still working to identify the individual(s) who detonated two bombs near the finish line of the Boston Marathon. Three people, including an 8-year-old boy, were killed. Another 14 are in critical condition in local hospitals. Dozens lost limbs.

The attack played out live and on camera. Within seconds of the explosions, spectators became rescuers and rushed in to assist the wounded. Photos and videos of the graphic aftermath were posted immediately on news sites. The images showed ordinary, everyday Americans applying pressure to wounds, holding the hands of the victims and getting them to safety. They were heroes because they had to be.

We are all, in a sense, eyewitnesses of the Boston Marathon tragedy. That is a blessing and a burden of the digital age. And like the dozens of other tragedies we have collectively witnessed through graphic, real-time images, we too will rush in to assist, to bind up emotional wounds and to help piece things back together. That is what we do, and it will ever be so. Evil may always be with us, but goodness always triumphs over evil.

I must admit it can be difficult to maintain faith in humanity when we are bombarded by human-caused tragedies on a weekly, sometimes daily, basis. It feels like things are getting worse. This is a natural reaction to the events we personally witness — our own glimpses into the heart of darkness force us to confront the fact that evil exists. Each generation has such moments and they will continue.

One such moment occurred 86 years ago next month in Bath Township, Michigan. A former school board treasurer named Andrew Kehoe planted 1,000 pounds of pyrotol and dynamite underneath the local elementary school. At 8:45 a.m. on May 18, the bomb underneath the north wing of the school exploded, killing 36 children and two adults. As rescuers rushed to the scene and began the grizzly task of recovering bodies and caring for the wounded, Kehoe drove up. He rolled down his window, called for the superintendent of schools to come over and detonated the bomb in his shrapnel-filled truck. This blast killed him, the superintendent and five others, including an 8-year-old second grader who had wandered out of the smoldering school. Forty-five people died and 58 were wounded in the bombings. The news of the Bath elementary school bombings spread rapidly. Thousands rushed to the scene to assist. Newspapers across the country told the heart-rending stories of loss and suffering. The nation mourned with Bath Township. Every generation has its tragedies.

Now, back to Boston. The debate in coming days will likely focus on what more we could have done to prevent the marathon bombings. I believe that is appropriate. But I also believe that it is important to acknowledge the limits of our abilities to control others. Determined individuals are capable of great evil. The warning signs of murderous intent are often difficult to spot. The Andrew Kehoes, the Adam Lanzas, the Timothy McVeighs are like ciphers in the shadows — unknown and obscure — until they are not. By then it is too late.

But goodness triumphs, even through tragedies. We are at our best as a people when circumstances are most critical. We run toward the danger instead of away from it, hoping to do some good. Collectively, we mourn with those that mourn and comfort those who stand in need of comfort. Such acts of compassion and courage give me hope for mankind in this dangerous world.

Dan Liljenquist is a former state senator and U.S. Senate candidate.