The simplest way to understand the military's dominance of Pakistan is to observe that it is what the citizen wants.
The expansion of this idea I will keep for another piece, but let's take a look at what Nawaz Sharif's third innings means for it.
In his first term, Sharif was said to be a figure of the military establishment. This was natural because the Sharifs were thought to have been encouraged by President Zia himself. I have a eulogy to Zia written by Sharif after the president's death which today will make for embarrassing reading.
The alliance of Islamists and the Muslim League was put together by the Inter-Services Intelligence against the Peoples Party, according to confessions made to a Pakistani court. But then Sharif showed independence and even defiance in his first term as prime minister and had to go.
His second term, beginning in the mid-1990s, was marked by two events. The first was an attempt in 1998 to create a Caliphate state, using the dormant clauses urging Islamicisation in the constitution and the Objectives Resolution. The bill was encouraged and possibly written by Sharif's father, who was active with the Tablighi Jamaat, and got one of its members, Rafiq Tarar, elected president.
The 15th amendment was to give Pakistan full Shariah law and one-man rule (to the extent that this is possible in South Asia, a chaotic place which is not fertile for authoritarian rule). The law would also, apparently by restricting the high executive office of Amir-al-Momineen to males, despatch Benazir Bhutto, Sharif's only political rival.
The National Assembly, under Sharif's 'heavy mandate', passed the law, but the MQM blocked the bill in the Senate, and there Sharif's gambit ended. The passing of his father in Saudi Arabian exile weakened the Tablighi influence on Sharif, and this aspect of him is no longer apparent.
The other interesting aspect of his second term was Sharif's sustained desire to normalise relations with India and open up trade. We must remember that this was in a period when the jihad in Kashmir was at its peak, India was under pressure and the rest of the world uninterested in Islamic militancy.
Even in such an environment, Sharif tried to reach out to India through another Punjabi across the border, the Janata Dal's Inder Gujral. Then he tried again with the Bharatiya Janata Party's Atal Bihari Vajpayee. Both times Sharif was enthusiastic.
The first initiative did not last, after the Congress pulled down Gujral. The second collapsed after the adventure in Dras and Kargil. Despite this we can conclude that Sharif was consistent and well-meaning in his effort to reach out. This is demonstrated by the fact that he has accepted the sequence of the souring of relations, ad correctly apportioned blame, even though this meant siding with India and against his army chief.
Another time Sharif has broken with the army to show his displeasure was after the killing of Osama bin Laden. He asked the army to give an account of its performance. Sharif did not follow through with this (because, to take us back to the opening paragraph of this piece, both he and the PPP sensed the national mood in favour of the army) but it showed us his thinking. He was not opportunistic and did not side with the military at a time when it would have been grateful for his support.
As he settles into his third term, from his office Nawaz Sharif has in view two things, across the border, he has a pacifist Punjabi who thinks trade and compromise are good for South Asia. Within his borders, Sharif has an army chief on his way out at the end of the year, but who is also one of the most realist leaders the military has produced (another reason for Pakistan to be grateful to president Musharraf).
For his part, Sharif has again hired the man, Sartaj Aziz, who according to stories almost struck a compromise with India on Kashmir.
The circumstances are right, and the people are in place for Sharif to finish what he tried to do in the years of his second term, talked about doing during his years in exile and opposition, and now has the chance to do in his third term.