On Friday morning the state news agency ILNA published the text of a letter written by Ayatollah Khomeini in the last days of the Iran-Iraq war. Giving his reasons for accepting a ceasefire, Khomeini revealed that Iran's war machine was totally exhausted and could no longer fight without a massive injection of money, men and, crucially, equipment, particularly in light of Iraq's widespread use of poison gas.
One item on a wish list presented him by the Revolutionary Guards stands out vividly: atomic weapons. This is the first time I can recollect any Iranian document coming to light that actually accepts the possibility of acquiring a nuclear bomb. The significance of this revelation in autumn 2006 was evidently not lost on the censors - within two hours of going up, the atomic reference was excised from the text, caught only by a BBC Monitoring sweep.
Khomeini quoted Revolutionary Guard estimates that the war could not be won for at least five years, and only then if Iran had the following equipment:

"350 infantry brigades, 2,500 tanks, 300 fighter planes and 300 helicopters as well as the ability to make a substantial number of laser and atomic weapons which will be the necessity of the war at that time. The strength of the IRGC must be increased seven times and the Military by two-and-half times."

But before anybody gets carried away, a word of caution. Khomeini at no point in the document suggests that he supported getting the bomb or that it would be religiously acceptable. All his known public utterances on the subject maintained that nuclear (as well as chemical and biological) weapons are haram (a position that has been carefully maintained by all other senior Iranian officials and clerics).
Khomeini also made it quite clear that obtaining this enormous new arsenal was out of the question: hence the necessity for a ceasefire. Historians might like to know that his famous quote "this decision is like drinking the poisoned chalice" was made in this very letter.
So why the need to censor it? The document implies that senior military strategists were actively considering the possibility of developing a nuclear bomb. And the timing chimes quite neatly with an acceleration in Iran's uranium enrichment programme in the late 80s and early 90s. Coincidence? Perhaps.
In any case, Iranian thinking on a nuclear bomb in 1988 must be considered in context: Iran was losing a bitter war in large part because of extensive WMD use by Iraq. Given that the international community had let Saddam get away with this for four-five years, Iranians could quite reasonably have concluded that the notion of collective security was dead and they needed their own WMD deterrant. Given Iran's dire military straits in the late 80s, it would be very surprising indeed if their military planners had not considered a nuclear option.

I happened to pass one of my favourite Tehran shops today, more than a year after my last visit. Mehran Press International at the corner of Sohrevardi and Takht-e Tavus looks as though it hasn't changed since it opened 35 years ago. Second-hand books are stacked from floor to ceiling inside and outside the shop, hitting you with a gust of musty old-book smell as soon as you walk past.
Quite often the owner is sitting outside playing chess with a friend, which is just as well because the piles of books take up so much room there isn't space for more than a single customer inside. When you start to browse the wall of English-language books you realise that every title, from best-selling thrillers to fashionable novels, dates from the 70s or earlier. Every book in the shop was left behind when foreigners fled the revolution.
There are plenty of kiosks that sell old English books this way, and a bookshop on Haft-e Tir Square, but somehow none of them has quite the same atmosphere of esoteric intrigue. I came away with Frederick Forsyth's The Odessa File, JG Farrell's The Siege of Krishnapur and Paul Scott's A Division of the Spoils.

Up around the Caspian in northern Iran are some of the most beautiful deciduous forests in the world - ancient Hyrkania. Known in Persian as jangal (the same word as jungle), they cover the northern foothills of the Alborz range, sitting just above the humid coastal plain, and running deep into the mountains. Boar, bear, wolves and even leopards still survive in the jangal, if you go far enough inside. Few people do - and on this trip neither did we.
I went with Gareth Smyth, the Financial Times reporter, and two other friends - K and H. It was the first day of school and the roads north were crowded with families returning late from holidays by the sea. The Caspian provinces - west-to-east Gilan, Mazandaran and Golestan - are the most popular holiday zone in the country, with sprawling grey resorts and chalet complexes running the length of the coast. It has been so since Safavid times, when the royal court retired here from Isfahan to wallow in the lush greenery and savour the widest variety of food in Iran. On the 'Shomal' section of the photo gallery are some more pictures of the region from previous trips.
The arid mountain road was terrifying. Iranian driving is reckless (some estimates say this country has the world's highest rate of road deaths) and the road curls rapidly down the side of a precipitous valley. After a while you just stop looking at the near misses in front of you.
But once in the forest, calm started to return. Many families had stopped by the road to picnic or break their return trip to Tehran. None had ventured from the picnic spot, right by the side of the busy road, where traffic noise drowned out conversation and exhaust fumes hung in the air. Roadside picnics are a peculiarly Iranian institution - with closeness to the car valued higher than splendid isolation. Litter is less of an issue than in the West too, with plastic wrappers, drink cans and other colourful debris proliferating everywhere but the bins.
We pushed on into the forest and climbed up the first ridge. Here, beyond the car noise and daytrippers, is a world of dappled morning sunlight and soft misty afternoons. The canopy of ash, chestnut oak and planes is far above, while smaller trees with delicate trunks stand up from the autumnal bed of leaves underneath. To look down a forested gorge or valley is to see back in time. You half expect a Mongol horseman to rear up from behind a rock, or to see the first Arab armies fearfully stalking through the undergrowth. For the record, it was the Caspian region that held out longest against both these - and almost all other - invaders.
Our own incursion was sadly short lived. The road was longer and more crowded than expected and we pushed on back to the city with a brief detour up an inviting mountain road, where the sun set over forested hills and valleys. A small village of only a few houses had escaped modernity. The local accents were impenetrable, the houses old, with outside loos and uneven plaster walls. A small mosque had the conical roof that replaces the dome for Caspian architects. A haunting azan rose as darkness fell - and we turned back for the main road.

I thought I'd kick this off with a quick description of how open people are in Iran. It's one of the first things you notice when you come here - especially if you're used to other Middle Eastern countries, where paranoia about state security is much higher.
Get into a shared taxi in Tehran and the chances are the driver and other passengers will be talking politics. As often as not, they'll be saying some very disparaging things about the government, specific politicians and other well known figures. Nobody bats an eyelid.
Last summer when covering the election, my translator and I were in a working class neighbourhood asking some people what they thought about the coming vote. A mullah happened to walk by and the people we were interviewing just started abusing him: "Look how fat that guy is," one of them shouted. "It's because they're eating all our dinners that there's nothing left for the ordinary folk."
Nobody had the least fear that they might be reported to the secret police or punished for this. An Iranian emigre friend who comes back here once or twice a year said this is very different to how things were under the Shah, when you were always looking over your shoulder before you criticised the government.
Sadly, that tolerance for what people say in private does not extend to the public sphere, where the regime punishes people with unrelenting hardness for even the mildest of criticism. The banning of Sharq, a very highly regarded pro-reformist newspaper, last week was just the latest example. The war on Persian-language bloggers and the filtering of Persian-language websites discussing politics is another example.
Many people are languishing in prison, some having gone through torture, for attacking the government in articles, books and blogs. And it certainly seems to be getting worse - as the several-month detention of academic Ramin Jahanbegloo showed earlier this year.
It means we foreign journalists are usually sure to get a wide range of opinions to put in our articles - but although these reflect how people feel, they are never seen in the domestic public sphere. Perhaps this is why private freedom of expression has never led to a genuine wide-ranging opposition movement inside the country.