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.
Image 1 of 7: Alexa Chung is an English television presenter, model and contributing editor at British Vogue. #bringbackourgirls Photo / supplied
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.