Whether or not his guerrilla kidnapers have killed him, Aldo Moro's long captivity ended the political life of this master of style rather than substance in Italian politics.

He holds the record - 829 days - for heading Italy's longest-lived Cabinet. He was the first Christian Democrat leader to form a fullfledged center-left government with Socialist participation. He is the one who sold the "historic compromise" with the Communists to reluctant Christian Democrats who wanted to rebel against the deal.

More is the master of Italy's "beautiful combinations," but his legacy of political accomplishment is very thin. The five successive centerleft governments he headed from 1963 to 1968 were full of promise but delivered very little.

"If Moro had been less of temporizer and a fixer and had instituted the basic social reforms this country needs," said a foreign diplomat, "it would not have gotten himself kidnaped."

Moro is one of the few Christian Democrat leaders about whom there was never any suspicion of personal corruption. But, characteristically, the other Italian political leaders have acted as if they feared that he knew about all the skeletons in their closets and that he would tell his Red Brigades abductors all about them.

The letters he wrote from his captivity do indeed seem to come from a man whose spirit was completely broken, so much so that one of the top Christian Democratic leaders was telling journalists privately that the party leadership had already made the basic decision that Moro was politically dead and could no longer be useful even if he comes through his ordeal alive.

Moro had been considered certain to win the Italian presidency in the election in December. The Italian president is elected by his fellow parliamentarians, not by the public, so Moro's introverted nature and lack of charisma did not make any difference in a political system in which the balancing of party factions is far more important than public opinion at a given moment.

As political leader, Moro had a gift for slipping into his turgid speeches the code phrase that signaled a change in policy. He was both a talker and a listener. He held a record for lengthy speechmaking - seven hours - at the Christian Democratic Party congress of 1962, and with his impassive demeanor, was considered the most patient of all the party leaders in listening to other people's long expositions.

Logic and clarity were not so important to him as political results. Thus he invented a famous phrase to describe the relations of the Italian left and right as "converging parallels.

Moro suffered something of an eclipsein the late 1960s, but as the Italian Communist Party came to occupy most of the left in politics and started campaigning for an alliance with the Christian Democrats, Moro's skills as a consensusmaker came back into demand, until he became the essential ingredient in clinching the deal.

Thus it was not an accident that the Red Bridgades chose him as the target of the first spectacular blow "against the heart of the Italian state" on the very day that the parliament was to start its debate on the agreement struck between the country's two major parties.

On paper, the agreement covered some of the basic problems Italy faces: public order and police powers, the overcrowded educational system and youth unemployment, increased decentralization of powers from Rome to the country's regional governments and stimulus for the ailing economy with aid to industries and increased investment in the perpetually backward south.

But there was plenty of room for skepticism that the government would turn out to be much more than another of Moro's "beautiful combinations." There is virtually no one on the Christian Democratic side who has voiced a grander vision than Moro's day-to-day conception of politics and no one, with the possible exception of Premier Giulio Andreotti, with the same talent as a conciliator of interests and factions.

The skepticism stems in part from the record of the Moro Cabinets as he presided over the end of the Italian economic miracle.

When Moro apparently broke under pressure from his captors, many Italian commentators said it was not entirely surprising. After all, they said, he had never been tested. A leader of the Catholic university movement before World War II, he spent the war teaching in a university in Bari in his native south. He emerged from the fascits era both unscathed and untried.

A modest man, he continued to teach law and to take his courses seriously. Unlike other Italian political leaders, he made a point of being available to his students and of continuing to sit religiously on the university boards before which they appeared for their oral examinations.

His pious personal lifestyle has also been modest and restrained. He has guarded his family's privacy jealously. Although he rejected the flamboyancy of some of his more colorful rivals in the Christian Democratic Party, he seemed to share their weakness for motion as a substitute for action.

Renowned for honesty and intellectual probity, he only reinforced the general taste in Italian politics for intricate abstract speech rather than talk about concrete problems.

Like most of his contemporaries in the Christian Democratic leadership, his political ambitions for Italy were not as large as the problems the country needs to solve.

Franco Ferraroti, head of the sociology faculty of the University of Rome, echoed the frequently heard sentiment that whatever people may say for the record, they were not that unhappy to see Moro Kidnaped because the state had not been very diligent in hinting for the many ordinary victims of kidnapings. The police have often urged the families of kidnaping victims simply to pay the ransoms. "The politicans," said Ferraroti, "did not pay attention until one of their own was kidnaped. People say it's high time one of them was kidnaped."