It is 110 degrees in the sun on the concrete campus of Qaid-i-Azam (''the great leader'') university here as a small, slight, young-looking figure in traditional long white shirt over baggy trousers invites a visitor into a bare office.
In soft, meticulous English (he has a PhD from the Massachusetts Institute of Technology) Ijaz Shafi Gilani proceeds to spell out blunt, Islamic fundamentalist opposition to the seven-year-old military government of President Zia ul-Haq of Pakistan.
Zia is ordering the official ''Islamization'' of Pakistan. But to Dr. Ijaz, a leading younger member of the Jamaat-i-Islami Party founded by one of the most influential thinkers in modern Islam, the late Maulana Abdul al Maududi, Zia is missing the essence of basic Islamic government.
''Zia has now banned student unions around Pakistan,'' Dr. Ijaz says above the hum of a ceiling fan. ''He has forbidden news of political parties from all the newspapers. This is not Islamic.... It could lead to the downfall of his regime. Until now we have not spoken out against him, but....''
* On an upper floor of a drab concrete office building in central Cairo, an elderly man of legendary reputation sits at a small corner desk, studying an Arabic newspaper.
This is Sheikh Omar Telmisani, the supreme guide of the Muslim Brotherhood, an Arab fundamentalist group founded by Hassan al-Banna in 1928. Officially banned in Egypt, it still claims much influence there, and in Syria, Jordan, Sudan, and the Gulf states.
The sheikh lost much weight but won much prestige among opposition circles after being thrown into jail in September 1981 by the late Anwar Sadat (who was assassinated by an extremist a month later).
Recently he came under attack for allegedly betraying al-Banna's principles. For decades the Brotherhood opposed political parties and called for government based on the Islamic law (Shariah). In the campaign for the May 27 elections in Egypt, however, Telmisani allowed Brotherhood candidates to run as candidates of the secular, liberal Wafd Party.
He tries to explain: ''We are still banned.... We need to take part in Shura (consultation) in the governing of Egypt.... Running for the National Assembly is the only way....''
Both these fundamentalist groups are strands of restless, orthodox, Islamic thinking around the world.
They and other Muslims believe themselves to be on the leading edge of a general revival of interest in Islam - a widespread determination to turn away from both communist atheism and Western materialism to a purer Islamic ideal of government.
So far Iran is the only country where fundamentalist thinkers have succeeded in overthrowing a secular, Westernized leader.
(The ''fundamentalists'' see themselves as closest to the ''authentic'' Islam of the Prophet Muhammad. This is a claim that is disputed by Muslims in Asia who believe they are following the ''true'' Islam. Asians tend to refer to Iranians and other radical Muslims as ''militant.'')
The fundamentalists, however, are forcing some concessions from, and are otherwise worrying secular rulers in Pakistan, Egypt, the Gulf states, Sudan, Nigeria, Indonesia, Malaysia, Cameroon, and elsewhere. Few rulers of Muslim states today can afford to ignore the appeal of fundamental Islam.
Future successes of the groups are uncertain. But their determination and activities are especially significant and intensified in light of the example set by Iran.
To fundamentalists in general, the urgent need is to throw off the influences of the 200 years of colonial domination by Europe. They want to reinstate the kind of Islamic purity that they believe led to the original Islamic surge across the world.
Beginning just after the Prophet Muhammad died in AD 632, Islam spread quickly through Damascus and Baghdad to North Africa and Spain to the west, Turkey to the north, and India to the east.
This is a pre-colonial perspective of history which the Christian world has largely lost, many Muslims say. Neither American nor European schools teach much, if any, of it.
The West does remember conflict, such as the crusades in the Middle Ages, sent to recapture Jerusalem from the ''infidels'' in the year 1099.
Islamic fundamentalists point to the achievements of the Arab empire before then, and to the recapture of Jerusalem by Saladin in 1187. Centuries of decline set in after the Mongols sacked Baghdad in 1258, and the Ottoman Empire defeated the Mameluk Sultanate in 1517.
Groups such as the Jamaat in Pakistan and the Muslim Brotherhood in various countries start by regarding Allah as having the only legitimate sovereignty on earth.
Members differ on how much independent judgment Muslims should use in interpreting ''God's will,'' but they follow the line of influential reformist thinkers Muhammad Abduh (1849-1905) and Rashid Rida (1865-1935) in stressing the need to base decisions and forms of government as closely as possible on the Koran itself, and on the sayings and the deeds of the Prophet Muhammad.
Both the Jamaat and the Brotherhood oppose arbitrary rule. Islamic government to them must be democratic - not necessarily one-man, one-vote, but based at all times on the principles of Shura or consultation. Individual Muslims must be allowed to express their views in some way.
In general the groups envision a central leader, an assembly to advise him, a separate judiciary to review laws and acts in light of the Shariah, and ministries to administer the laws.
Strict Islamic punishments for law-breaking would be enforced, together with the stringent conditions (largely unknown in the West) laid down for their enforcement. Discotheques, alcohol, pork, interest on loans and bank deposits, lotteries - all would be banned.
Among issues unclear to outsiders is how Sunni Muslims would effect change if a ruler became unjust. The Sunni tradition avoids violent uprisings. In general it urges obedience to constituted secular authority.
One prominent thinker, who was born Leopold Weiss in Central Europe but converted to Islam under the name Muhammad Asad, has suggested that Muslims need not obey laws they regard as sinful, but that only an open vote by a majority can depose a leader. How this would work in practice has never been tested: Critics say it sounds too passive.
Another Western criticism is that minority non-Muslim groups may be discriminated against in an Islamic state.
Both Christians and Jews are specifically approved in the Koran, but in the past, the Bahai sect in Iran and the Ahmediya sect in Pakistan have been singled out for harsh treatment.
One effort to counter this image comes from the right-of-center Islamic Council based in London. Its secretary-general, former Saudi diplomat Salem Azzam, said in an interview that any Islamic government must include one-man, one-vote representation, and a constitution that guarantees basic human rights and the rule of law.
''You can't be a Muslim if you build a mosque, then violate human rights,'' Mr. Azzam said. ''Yes, the Iran-Iraq war, the fighting in the Sudan, the violence of Libyans abroad, are all bad for the image of Islam in the West. But Islam itself is innocent.... We hope the Western media will look deeper into Islam, to see that it is a civilization, a culture, a religion. These it doesn't know. We all have the right to know what different religions stand for.''
Muslims concede that no Islamic government based solely on the Koran and on the Prophet Muhammad as yet exists.
The Shia Muslim revolution in Iran has perhaps gone furthest toward it (and interestingly, Mr. Azzam defends it in part: ''It wasn't a coup d'etat. Most Iranians still support it. Western media reports are biased against it and there's no freedom of the press in the Arab world either to report it objectively.... Many of those killed since 1979 have been drug traffickers and criminals.'')
In the majority Muslim world of the Sunnis, Saudi Arabia claims that its entire Constitution is the Shariah itself, though its ruling royal house of Saud has no democratic basis.
By no means are groups such as the Jamaat and the Brotherhood the most extreme of the fundamentalists.
Smaller and more radical groups exist in Egypt, in Lebanon, in Kuwait, and elsewhere, with names like Jihad, Takfir wal Hegira, (''Repentance and Flight'') , and Hizbullah (''Party of God'').
At the furthest edge of the restless Islamic thought are the individuals who turn to violence and assassination: Khaled Ahmed Shawki el-Islambouli, for instance, the former Egyptian Army lieutenant who led the successful attempt on the life of Anwar Sadat in October 1981.
Both fundamental and extremist groups are feeling a certain impetus from events in Iran, despite Tehran's long-drawn-out war with Iraq and continued economic difficulties.
In the short term, Shia Iran's example has failed to fire immediate revolutionary efforts by Sunni Muslims in other countries. Yet many Muslims say its continued existence remains a powerful example over the long term.
Iran has tried its hand at exporting rebellion. It has sent Revolutionary Guards to work with Lebanese Shiites including the Hizbullah and the Islamic Amal, whose troops plastered pictures of Ayatollah Khomeini on walls when they fought their way into east Beirut earlier this year. (The pro-Iranian Al Dawa group in Iraq was also linked in press reports to the bombing of the US Embassy in Beirut in October 1983.)
The Ayatollah has also tried to infiltrate Shia religious communities in Pakistan and elsewhere, according to Muslim informants. Yet he appears to have had little success so far.
Shias abroad remain attached to their own institutions and countries. According to other Western reports, most Lebanese Shiites respect Khomeini in religious matters but have their own ideas about Lebanese politics - which revolve around using the multiparty system there to extract as much advantage for themselves as possible.
Iran's influence could be more worrisome to the nearby Gulf states, where Shiites live in considerable number.
Pro-Iran Shiites in Kuwait are taking part in a current Islamic effort to reform freewheeling Kuwaiti society (though bombings of US and French embassies in Kuwait last December, and of industrial sites, have been linked to pro-Iraqi Shia groups).
In a ground-floor office at the American University in Cairo, a noted Arab scholar explains why fundamentalism could still burst into violence in Egypt and elsewhere, despite a current period of calm.
Speaking in calm, excellent English, black-bearded Saad Eddin Ibrahim says what he calls ''militant Islam'' is growing among young college students in Egypt, Syria, Saudi Arabia, and elsewhere.
''These young people have four kinds of misgivings about society,'' Dr. Ibrahim says. ''They see a lack of opportunity when they graduate. Egypt's cities are overcrowded. Good jobs are hard to find unless you are elite, speak English, and work for a foreign bank or a multinational corporation.
''They see the economic system as having failed: not enough development industries.
''They feel Egypt is dominated by the United States and humiliated by the existence of Israel. They see Western blue-jeans and Coca-Cola subculture swamping them.
''These youngsters are young, sensitive, vulnerable, uprooted from their villages, looking for a sense of belonging. There are hundreds of thousands of them.''
President Hosni Mubarak has so far eased tensions by working to integrate militants back into society. He has allowed young militants to debate Islamic scholars on Egyptian television and let them write articles for new Islamic publications.
Crucial, Dr. Ibrahim believes, is whether the militants see the May 27 Egyptian elections as having been fairly and freely held.
Another veteran observer of the Middle East in London commented: ''All these points about Egyptian youth could be made with equal force about young people in Syria as well....''
One more element of orthodox Islamic thought is represented by the so-called Sufi brotherhoods, which resemble Roman Catholic orders.
Ranging from austere groups to others who chant and sway, they consist of Muslim believers each following an individual ''holy man'' or leader, praying with him regularly and performing extra prayers and other religious exercises.
Over 100 separate orders exist today, some of them 1,000 years old.
In the past these orders, many of which contain elements of mysticism, have appealed to Asians and Africans in particular and have helped spread Islam in north and sub-Saharan Africa as well as in Libya, Sudan, and elsewhere.
According to some Western scholars, there is clear evidence that they are helping keep Islam alive in the Soviet Central Asian states of Uzbekistan, Kazakhstan, Tadjikistan, Kirghizia, and Turkmenia.
The grand sheikh of Sufi orders in Egypt, Dr. Abu el Wafaa el Tafpazani, says 67 orders exist in Egypt alone, with 3 million members.
He describes the orders as the ''moral philosophy'' of Islam, separate from politics but serving as an underpinning for the Muslim faith.