In a world where terrorist atrocities are almost a daily event, it is easy for a certain indifference to take root. But every so often there is an outrage that so oversteps the bounds of humanity that it demands the world's attention.
The murder of Israeli athletes at the Munich Olympics was one such occasion. So, too, was the taking of schoolchildren as hostages at Beslan 10 years ago.
To those episodes can now be added the abducting of more than 200 teenage schoolgirls in northeast Nigeria. This is a particular challenge because Nigeria, unlike West Germany and Russia, appears incapable of mounting a coherent rescue operation. It is, however, a challenge that must be met.
As much is underlined by the fate of the girls if nothing is done. Their captor, an Islamic extremist group called Boko Haram, has threatened to sell them as slaves. Already, some of the girls may have been shifted across the border to Chad and Cameroon and sold as brides, making them increasingly difficult to track.
With almost a month having elapsed since they were kidnapped from their school in a pre-dawn raid, the time for a successful response is rapidly dwindling.
Much of the blame for that must rest with the Nigerian Government. President Goodluck Jonathan seems initially to have seen the abduction as simply another incident in a decade of conflict with Boko Haram.
The terrorist group wants to establish a medieval-style caliphate in the north of Nigeria, and is particularly opposed to Western-style secular education.
Most recently, it has become more violent leading to the death of more than 1500 people this year. In the process, it has demoralised Nigeria's Army and seemingly blinded the Government's sensibilities.
The rest of the world was also slow to respond. That, in itself, says something about how much it takes to stir people in a world where terrorists, out of necessity, select soft targets.
Now, however, there is a recognition that the enormity of this outrage demands a response.
The United States Secretary of State, John Kerry, has labelled it an "unconscionable crime", while the British Foreign Secretary, William Hague, said that using girls as the spoils of war was "disgusting" and "immoral".
What they can do about it is more unclear given the size and denseness of the Sambisa Forest, where the girls were taken.
Nigeria, fortunately, has finally accepted the need for help. The US has sent military personnel and hostage negotiators. Satellites and drones will be being used to try and locate the girls and track the terrorists' movements. If this is successful, a decision must be made about sending in special forces.
There is a major risk that some of the girls will be killed in such an operation, as happened at Beslan. That should make it a last resort. First, there must be an attempt to negotiate with Boko Haram, as unpalatable and as unlikely to succeed as that may be.
Only one thing is certain: Boko Haram has extinguished any prospect of support for its cause from all but the most rabid of sources. That is the inevitable result of stooping to using children in a way that so deliberately flouts accepted values.
Confronting it over the Chibok schoolgirls must be the prelude to the international community helping Nigeria eliminate it as a threat.