Iran: A Modern History. By Abbas Amanat. Yale University Press; 1,000 pages; $40. To be published in Britain in January; £30.

ABBAS AMANAT is an authority on Iranian culture and political history. In his new book he presents the past five centuries of Iran’s history in its Persian, Shia context. At 1,000 pages, it is not for the fainthearted. But Mr Amanat is a skilful narrator whose use of sources and anecdotes is illuminating. His book should be read by anyone who is curious about the history of political philosophy and ideas.

It is especially strong on cultural, literary and intellectual history and the role this has played in Iran’s interpretations of political and clerical authority. Mr Amanat dips into the lives and works of key figures, from those who articulated the country’s responses to European imperialism, such as Mirza Malkom Khan, a prominent modernist who died in 1908, to the ideologues of the Islamic revolution of 1979. These include Jalal Al-e Ahmad and the left-leaning zealots and poets who used a mix of Marxism, Islamism, the Shia tropes of martyrdom and Frantz Fanon’s third-worldism to give Iran’s Islamic revolution its distinctive characteristics.

It is Mr Amanat’s ability to draw out the bigger themes in Iran’s history as a Shia powerhouse state that sets the book apart. He begins with the creation of the Safavid state in the early 16th century. He explains the competing tensions within Persian Shiism of temporal and spiritual legitimacy, intertwined with messianic revivalism, mysticism and dissent. Put simply, in a battle between God and the crown, who wins what, and why?

Until 1979, the state had the upper hand. The clergy were there to preach, educate and sit in judgment on the nation’s souls. A politically active clergy was, and still is for many leading Shia thinkers, a heretical innovation. Mr Amanat excels at establishing, through events and through the thought of its leading philosophers, how Persian Shia political philosophy creates this natural separation of mosque and state, as long as the state allows freedom and safety of Shia religious practice.

Mr Amanat highlights another important point in Iran’s politico-religious make-up when he traces the cyclical nature of divine revelation in “Twelver” Shia thought, through the 12 imams (descendants of Prophet Muhammad), and the 12th imam’s “occultation” in 874. This facet of Shia philosophy offers Persian political culture the potential for millenarian trends to appear at times of political and social crisis. President Mahmoud Ahmadinejad’s conviction that the 12th imam was poised to return to daily life in Iran meant that, among other less innocent actions, he would lay an extra place for the 12th imam at his weekly cabinet briefings. Ayatollah Khomeini came to be known as an imam, which constituted a break with the notion of a quietist, apolitical clergy. This was heretical among local Shia communities and yet also had precedent in Iran’s modern history, as Mr Amanat illustrates.

The exploration of this central tension lends Mr Amanat’s account of the Islamic revolution a deep historical resonance. The book traces this tension through Iran’s turbulent engagements with Western imperialism into its later entanglements with 20th-century superpowers. Central to the debate surrounding the constitutional revolution that began in 1905 was the place of Shiism in Iranian political life. Would the clergy retain their control over sharia law and its role in shaping private life, or would they be subsumed by the advance of secular Western political ideas?

That question came to dominate the nation’s political discourse, often under the shadow of real and imagined threats from the West. Ayatollah Khomeini’s controversial doctrine of velayat-e faqih, the “guardianship of the jurist”, and its application as the ideological and constitutional blueprint for the Islamic revolution, was the first time in Iran’s Shia history that the clergy had explicitly articulated a theory of government. Before that they always preferred to remain scholarly and juristic.

Derided under the Pahlavi monarchs and sidelined in the dash to achieve Western modernity after the discovery of oil, the clergy launched the Islamic revolution as an act of revenge. Their bid for power challenged the very soul of Shia orthodoxy. It was not a complete triumph, for the 1979 revolution and its aftermath crushed the clergy’s centuries-old independence from the state.

Despite the book’s extraordinary range and detail, the reader is left wondering about the ultimate place of Islam and politics in Iran, and how this might develop. A legitimate question is whether the Islamic republic of Iran has been the harbinger of the destruction of the Iranian clergy, both in the minds of the Iranian people and as a political force. Have the clergy become so crippled by association with the horrors of the Islamic republic—with its mass purges, its political prisoners raped and tortured, and the children who were forced to walk over minefields during the Iran-Iraq war—that they have lost all moral authority with Iranians? Might there be an upsurge in orthodox clerical opposition to the Islamic republic as this uneasy experiment in Shia political activism comes to an end of sorts?

Mr Amanat does not address these questions, but perhaps he does not need to. He ends with the disputed elections of 2009 in which Mr Ahmadinejad controversially returned to power amid repression and violence. The writing might, one assumes, be on the wall.