He is seldom seen in public. He does not do TV interviews. He communicates only through written edicts or through lower-ranking members of the network of scholars who study the Koran and Islamic law in the provincial town of Najaf. And yet the 75-year-old Grand Ayatollah Ali al-Husseini al-Sistani is undoubtedly now the most powerful man in Iraq. Revealingly it has taken almost a year for George Bush to wake up to that fact.
The events of this week have underscored the importance of the venerable Shia cleric who in January called 100,000 demonstrators on to the streets of five key cities to protest against America's refusal to allow immediate direct elections in Iraq - and who, more significantly, was able to send them all back home, with the ease of a man turning off a tap, when he had secured the concession from the Americans he had been seeking.
This week, when 180 pilgrims were killed by bombs targeted at the Shia community, could have seen the start of a civil war between Shia and Sunni Muslims, but the Ayatollah swiftly clamped down on talk of retaliation.
But he was happy to scupper the signing by Iraq's provisional Governing Council of an interim constitution yesterday to pave the way to the transfer of sovereignty back to Iraqis and the holding of full elections. At the behest of the Ayatollah five Shia members of the council refused to append their names .
What is becoming clear is that Ayatollah Sistani represents the most significant political challenge encountered so far by the US-led coalition. Twice already he has forced Washington to rewrite its political road map. At his behest the US has reversed its plan to write a constitution before elections: the elected assembly will now write the constitution. He has also successfully demanded that the United Nations be brought in to assess the feasibility of the elections.
None of this is what the US viceroy Paul Bremer III had expected. The elderly cleric, with long white beard and black turban - indicating that his family claims descent from the prophet Mohammed - may have looked reminiscent of the great American hate figure of the 1979 Iranian Revolution, Ayatollah Ruholla Khomeini, who introduced theocracy to the modern Middle East, but he had not been expected to behave like him.
One of only five living grand ayatollahs in the world, Sistani was said to be of the "quietist" school of Islamic tradition. He had, after all, lived in uneasy stalemate with the Saddam regime, spending long periods under house arrest and largely staying out of politics. And in the early months of the US occupation he had seemed malleable enough. His initial response to the invasion was to advise "believers not to hinder the forces of liberation, and help bring this war against the tyrant to a successful end for the Iraqi people". What the Americans failed to note was that he added that Iraqis working with the occupiers should ask, at the end of every conversation with them, "when they were leaving".
Had they been more diligent they would have worked out Sistani's influence much earlier. They should have noticed that Sistani receives millions of dollars in donations and controls a network of schools, mosques, clinics and other social welfare institutions. They should have observed that when, in the early days of the occupation, Sistani spoke out against looting, it died down rapidly in Shia areas. And when he issued a fatwa against the black market in petrol, queues at petrol stations immediately shrank by 75 per cent.
They should have seen the significance of the fact that - though he gave private audiences to members of the US-appointed Iraqi Governing Council and the UN Special Representative, Sergio Vieira de Mello, who later died in a Baghdad bomb - he consistently refused to meet American officials. He was positioning himself for the long term.
Events have placed him well. One by one the other main clerical leaders have been killed. Ayatollah Muhammad al-Hakim, Saddam's principal Shia enemy, died in a car bomb in Najaf recently after returning from 24 years' exile in Iran. Abdul Majid Khoei, the son of Ayatollah Sistani's predecessor as the highest Shia religious authority in Iraq, was also assassinated in Najaf last spring when he returned after 12 years' exile in London. The leader of the other great clerical family, 30-year-old Muqtada al-Sadr, son of the great Ayatollah al-Sadr famed for preaching in a shroud, who was killed by Saddam in 1999, does not have the religious credentials to be a serious rival.
Ayatollah Sistani's prime influence comes from his status as Shi'ism's leading marjah al-taqlid, the title (literally object of emulation) given to a cleric whom Iraq's 15 million Shia Muslims regard as a guide in every aspect of their lives.
Born in Mashad, Iran, 75 years ago, the young Ali began studying the Koran as a youthful prodigy at the age of five. He has lived immersed in Islamic study ever since, first as a student in Qom and then for the past four decades in Najaf which has been the centre of Shia learning for 1,000 years. He has studied philosophy, rhetoric and law under the great scholars of his day and has developed a reputation for penetrating to the "real meaning" behind the words of key Islamic texts. His followers speak of his holiness, personal asceticism and intellectual rigour characterised by a keen interest in modern science, economics and international politics.
Most revealingly he is a specialist in ijtihad, the use of reason to apply Koranic values to contemporary situations - a discipline which only the most distinguished Shia clerics are allowed to practise. (The "gates of ijtihad" were closed to Sunni Muslims 1,000 years ago.) This allows Islam to be reinterpreted in light of changing circumstances.
Thus Sistani's website concerns itself with such contemporary obsessions as whether Muslims can use perfume which contains alcohol (yes), use interest-bearing investments (in some circumstances), gamble (on horses but not lotteries), masturbate (no), perform anal sex (yes, though it is "strongly undesirable") or oral sex (yes, so long as no fluid gets into the mouth). All of which is some distance from current Western values but which at least offers the possibility of engagement with the West in a way which is inconceivable with such Sunni fundamentalists the Taliban, al-Qa'ida or the Wahhabi puritans of Saudi Arabia.
There is another interesting strand in his thinking. One of Sistani's fellow students in his early days in Najaf was Ayatollah Ruholla Khomeini who believed that, left to their own devices, most people would not live by Islam's precepts and so developed a doctrine of clerical dictatorship - velayet-e faqih (the Regency of the Jurist), which was the basis for the Iranian revolution. By contrast Sistani repeatedly stresses that religion has to be separated from government.
Where Khomeini in his 14 years in exile in Najaf argued that "only a good society can create good believers", Sistani insisted the opposite: "Only good men can create a good society." Today, about a third of Iraq's 15 million Shia follow the Khomeini line; the majority follows Sistani.
This is obviously of considerable political significance. It highlights Sistani's current dilemma. His theological position insists clerics should not interfere in government. "The clergy are the conscience of society," he has written. "The administrative aspects of society's life must be left to men of politics." Yet he believes that at present Iraqi Shia need some leadership, which can come only from their clerics, to develop the political framework in which religion and politics can have their distinct spaces.
There is clearly scope for much confusion here. Sistani has said that no law in Iraq should conflict with Islamic principles, and he wants Islam to be recognised in law as the religion of the majority of Iraqis. But he wants to secure a model which will mean that a future secular regime cannot pass laws that contradict Islam rather than establishing a state along the Iranian model.
The best way of ensuring this, he sees, is through the pure democracy of "one person, one vote". This is why he opposes the complex structure designed by the Americans to ensure that the Shia majority cannot ride roughshod over the educated Sunni elite and the autonomy-craving Kurds. It produces the peculiar irony of an unelected mullah pressuring the world's self-styled greatest democracy to implement the self-determination it ostensibly invaded Iraq to bring. Sistani summed that up in a recent letter to the US administrator which said: "Mr Bremer, you are American. I am Iranian. I suggest we leave it to the Iraqis to devise their constitution."
There are those who worry that once Sistani has had a taste of power his demands will grow rather than recede. The handful of people - including Sunnis, Kurds, secularists and women's rights campaigners - who have recently had audiences with the Ayatollah in his modest home off a crowded market street in Najaf are more sanguine.
"He didn't use any of the rhetoric clergymen usually wrap everything they say with. He was quite plain and direct, though he talked so softly, almost in whispers, in a heavy Persian accent," said one. "The man was secular! I have never heard a clergyman saying the things that we lot take to represent our secularism," said another.
"He talked about the ancient pillars of the Sunni doctrine and praised them in detail and said how the difference between the Shia and Sunni was far less significant than the danger facing the Iraqi nation at present," said a third. "They told me he wouldn't meet with a woman," said a female politician, "but I met him and discussed women's issues."
There are many people fervently hoping that Grand Ayatollah Sistani will prove true to his word. Not least among them George Bush in the coming election year. "He's Hobson's choice for the Americans," one commentator said, "but it could be a lot worse."
We might let the Ayatollah himself have the last word. He recently gave advice to a politician about to put someone forward for office. "Whoever you nominate, make sure he's not wearing a turban," Ayatollah Sistani said. The question is: will he apply that maxim to himself?
A life in brief
Born: 1929 near the Iranian city of Masshad, a site of Shia pilgrimage. Lives near the Iraqi holy city of Najaf.
Education: Began studying the Koran aged five, then philosophy aged 11. Apprenticed to a succession of eminent Muslim scholars.
In 1949 he joined the Islamic seminary in Qom, Iran, to study jurisprudence under Grand Ayatollah Sayyid Hussain Brojardi.
Career: 1952: moved to Najaf to study with some of the most important Shia clerics of the time, including Grand Ayatollah Imam Abul Qassim al-Khoei.
1992: selected by his peers to head the most important hawza, or network of schools, in Najaf. Has written many books on Islamic law and gained a reputation as one of the top Shia religious authorities in the world.
He says...: "Mr Bremer, you are American. I am Iranian. I suggest we leave it to the Iraqis to devise their constitution."
"The clergy are the conscience of society. The administrative aspects of society's life must be left to men of politics."
They say...: "Sistani represents the middle of the road in Iraq's political spectrum... We have to listen to and deal with what Sistani is saying." - Judith Yaphe, National Defense University, Washington DCReuse content