David Rudisha is one of the greatest runners of all time. If you have never heard of him it is most likely because his chosen distance of 800 metres falls between the power glamour of the sprinters and the aesthetic elegance of the long-distance specialists. At the 2012 London Olympics he smashed his own world record to win the gold medal.

Not only was the race run in a staggeringly quick time, it was won with a deceptive ease that belied the hours and miles of gruelling training that came together in less than two minutes of athletic grace. Watch the race on YouTube and you will see an athlete at the peak of his abilities.

David Rudisha is Kenyan. He comes from a long line of outstanding Kenyan Olympians (including his father who won a silver medal in 1968). Their determination on the track – and humility off it – has given Kenyans so much pride not just in their sporting heroes but in their beautiful country as a whole.

That pride and confidence has been replaced for now by the shock and abhorrence at what unfolded last Saturday at the Westgate shopping mall in Nairobi. Kenya is no stranger to terrorism or occasional outbursts of political violence. But the way in which the Westgate attack was played out almost in slow motion, in front of the world’s media and captured vividly by the victims on phone cameras should ensure that this atrocity becomes one of those horrible iconic moments in the terrorism almanac. And the presence in the shopping centre of so many non-Kenyans means that it will be internationally symbolic in a way that the double suicide attack the same weekend in Peshawar in Pakistan – despite its similar depravity and higher death toll – will not.

As the immediate shock recedes, the difficult process of evaluating what this attack means for Kenya begins. Tourism along with agricultural exports is one of the bedrocks of the Kenyan economy and will now inevitably suffer; at least for a while, until – in the absence of further major attacks – the lure of Kenya’s extraordinary natural beauty proves irresistible again.

But there is more to Kenya than safari parks and beaches: the country is on the brink of an oil and gas revolution that stands to have a major impact not just on Kenya but on the whole region. This will bring potential hydro-carbon wealth and an infrastructure boom as well, the most conspicuous project to date being the Chinese-funded super port in Lamu. Was the Nairobi attack an outlier event, a desperate move from an organisation – al-Shabab – in retreat or was it a terrible harbinger of growing extremism and instability in East Africa? And does Kenya have sufficiently strong political institutions to restore national and international confidence?

These are the kind of questions that are now being asked by existing and potential investors as they calibrate what this means for the longer term. It is too early for definitive answers. But the golden rule in these situations is never to be swept along by the pessimistic hyperbole that inevitably gets peddled by the professional doom mongers. Most countries and all people are more resilient than they seem and nearly all terrorist organisations are less powerful than the asymmetric image they choose to project.

In some ways it seems a little callous to talk of re-evaluating investment risk while the terrible human toll is still being counted. But there is a place for calm re-assessment as an antidote to over-reaction. It will be to Kenya’s benefit for the awful events of last weekend to be seen in sober context and the images of desperate families running for their lives to hide from roaming gunmen replaced by the more familiar and inspirational sight of Kenyans running for the pride of their country.