Selfless sensibility

For Lawrence DePrimo, a freezing night earlier this month was just another shift. The 25-year-old officer was on his usual patrol, representing New York Police Department in his home city.

Days later, however, the events of the evening had made DePrimo an online phenomenon.

He had encountered a homeless man, barefoot, and shivering in the freezing cold. Concerned, he spoke to him for a few moments. Then, the young officer walked into a nearby store, and, with his own money, bought the needy man a pair of winter boots.

Though he didn't know it, a passer-by had snapped a photograph as DePrimo knelt to put the boots on the man's feet. She sent it to the New York Police Department, and it was posted on its Facebook pageLike many public authorities, the NYPD has recently established a social media presence to interact with the people it serves. NYPD's Facebook page promotes community work the force has been involved in, and its Twitter feed shares important news. DePrimo's photograph is by far the most successful update to have been posted on the Facebook page so far.. The story has attracted over 600,000 likes, and comments from as far afield as Spain and Armenia.

'Thank you for showing kindness in a world that is not always kind,' said one Facebook user. 'Generous, humble and drop dead gorgeous' swooned a new female fan.

DePrimo's reaction, however, was more reserved. 'I didn't think anything of it,' he said in an interview.

For the young officer's new fans, that makes his story all the more remarkable: this act of kindness, they suggest, was motivated not by a need for recognition, but a genuine need to do the right thing.

Such secret Good SamaritansThe parable of the Good Samaritan, told by Jesus, appears in the Gospel of Luke. It tells the story of a man dying by the side of the road, who is ignored by two respectable passers-by, then helped by a Samaritan - a member of a minority often demonised in Jesus' time. often capture the public imagination. In 2010, New York united in search of a 'Mystery Frenchman' who had saved a drowning baby before disappearing without applause. And earlier this year, a German town garnered international attention when an unknown benefactor began leaving envelopes stuffed with cash at local hospices, soup kitchens and schools.

But this kind of altruism could be a rare thing. In a recent Yale study, five-year-olds were put in a situation where they had the opportunity to share. Those believed they were being watched were likely to show generosity - but the children who believed no one was looking kept their toys to themselves.

Are charitable acts more significant when they are hidden? Only those who do the right thing without an audience genuinely have the needs of others at heart, some say: in public, people's actions are all too often swayed by a desire for recognition and status. 'Our character,' as writer H. Jackson Browne once wrote, 'is what we choose to do when no-one is looking'.

Other disagree. When someone does something in public, they act like the person they want to be. The things people commit to in front of others demonstrates values that they have thought about carefully, and want to share with the world. That, some argue, is a more important sign of morality than what they do behind closed doors.