Fall of Constantinople by Fausto Zonaro.
Some years after the Ottomans defeated the Byzantine Empire in the mid-1400s, the men of power around the ruling Sultan grew weary of the corruption of the bureaucracy they'd inherited and established a new system of integrity testing to weed out their less enthusiastic workers.
According to Middle Eastern scholar, Dr Graham Leonard, these auditors would pop up all over the empire "to find out are you doing your duty, are you doing it with a smile, are you doing it quickly?"
As he describes it, life in the public service wasn't much different half a millennium ago, half way across the world: "What happens in a bureaucracy? If I get a job with the government, I've got a lifetime meal ticket and, so, I don't do anything more than I have to, because I'm going to get promoted because I've been years and years in the service, whether I'm any good or not.
"Bureaucracy grinds to a halt," says Leonard in a lecture series recorded at East Tennessee State University in 2009.
Of course, all public servants do not have this mindset but, I think we've all had dealings with bureaucracy and, for that matter, private companies and big corporations, where the provider of a service is simply not providing that service.
"Well, you couldn't do that in Turkey because if an auditor caught you ... they'd take away your salary for three months or a month. Next time they caught you they might suspend you. Next time, no job," says Leonard.
Of course, the Byzantines didn't earn their reputation (i.e. "relating to, or characterized by intrigue; scheming or devious; highly complicated; intricate and involved") for nuffin.
Says Leonard: "This [system of auditors] didn't work very well because in those days transportation was difficult, so that people in Tunis would get news the auditors were in Tripoli and probably coming to Tunis, so everyone would behave nicely for a while."
Around the 1600s, the Ottoman government dreamed up a new idea - secret auditors, who did not announce their station or their arrival - and conscripted beggars, students, scholars and pilgrims to Mecca to test the bureaucracy wherever they happened to be.
(In those days, Islamic scholars and students travelled constantly from teacher to teacher, pulling up stumps once they'd learned all they could, then moved onto the next person of knowledge).
Says Leonard: "They would give half of a seal to these secret auditors and I'd come in and I was just a beggar and you'd treat me like dirt and you'd be out of a job because I'd take my half of the seal and, I'd go find one of the three ruling jannisaries.
"He'd have the other half of the seal and we'd put the two together and use it to put a stamp on your record and cause you trouble," says Leonard.
"This worked wonderfully from about 1600 to 1800, maybe 200, 250 years," says Leonard, until the jannisaries gained the power to actually name the Sultan, and once they did, that Sultan disbanded the secret auditors altogether.
"By 1850, they'd gotten rid of all auditors. By 1900 the bureaucracy was so corrupt it was not really working any more and Turkey was then called the 'sick man of Europe'," says Leonard.
Leonard by no mean suggests the fall of the Ottoman Empire was a result of the loss of these secret auditors and outlines many other factors, but it's an interesting story of how accountability keeps people honest.
I started thinking about the secret auditors last week when I read of Aussie NBA star Andrew Bogut, ripping into Telstra on Twitter about the problems he had getting his wireless router installed.
"Passed around and around. Problem still not solved. Wait another 72 hours they say," wrote Bogut, expressing a frustration we've all experienced with one company or another.
However, the rest of us are not Australia's highest paid sportsman. When we scream in cyberspace, no one hears.
Or do they?
It seems to me companies are becoming increasingly sensitive to the way they are portrayed online because traditional advertising has fallen off a cliff.
Part of that is the decline of news print advertising but, another part of it, I'd speculate, is that consumers are now hearing their concerns and scepticism about many companies confirmed and amplified via the internet.
If you had a problem with a company years ago, unless you chanced to talk to someone who had the same problem, you probably just put it down to a one-off or bad luck.
But as campaigns like #vodafail have shown, when we realise we are just one of many and that problems with a certain service provider are widespread and common - we get angry.
In this regard, the internet, and particularly the Twitter hash tag, has delivered us all half of the secret auditor's seal. We need only pair it with another user's half seal - their bad experience - and our complaint is corroborated and legitimised.
It may not cause as many waves as an Andrew Bogut does with his 90,000 followers, but it does mean that even the smallest customer now has the potential to cause trouble.
Be nice to beggars, I say.