LATE in his life Nelson Aldrich Rockefeller mused aloud to some of his staffers: "If I really wanted to be president that bad, I should have done what Dick Nixon did . . . that is, take two or three years and just concentrate on the science of how do you influence and get the contacts to get the votes. . . . I never really made a full-time occupation out of trying to get the nomination."

Sour grapes, maybe--or perhaps a basic truth about how people become president in our time. In either case, a commentary on what's probably going to be our central memory of Nelson. He was the man who would be king, but never got higher than lord lieutenant.

In Rockefeller's own view, as expressed above, this was a case of grandeur unappreciated. He "failed" because he was wedded to achievement, and did not pause to scratch the right backs. And some political historians would lay it to the bizarre fact that this genuine conservative was considered too "liberal" to head the ticket by the regular Republicans who regularly become convention delegates. In their rightward-tilted world, anyone who is not Reagan or Goldwater is suspected of closet socialism. It is even possible that Rockefeller's divorce in 1961 denied him his chance to lead a nation.

But whatever the reasons, the story may be less heroic and tragic than Rockefeller believed. He saw himself as the answer to needs of his day--a creative problem-solver and builder, who could use his gargantuan assets for everyone's good by hiring the best brains available. Yet any careful reader of this biography can't avoid wondering if "Rocky" himself was not a man of small mental capital who would have been lost in the shuffle without the clout of his multiple millions.

Joseph Persico never voices this speculation straight out, but his book flutters around it from beginning to end. It is not a "full" biography. It touches lightly on Nelson's relations with other grandsons of the Founding Oilman, on his artistic interests, and early government service as a Latin- American expert. It's properly discreet about Rockefeller's marriages and love affairs, saying nothing not already familiar. It says little on Rockefeller's term as vice president, which drove him crazy as it does any active man sucked into its limbo. Its true centerpiece is the story of Rockefeller's 15 years as governor of New York, during which time Persico was one of his speechwriters.

Persico loyally asserts that "Rocky" was a first-class governor, whose bold and imaginative programs of urban redevelopment, support for the arts and the state university, and environmental concerns rate the highest praise. But he makes it clear, too, simply by his dispassionate insider's recollections, that Rockefeller was not a major figure. He was--if Persico is accurate--humorless, insensitive, unread, ungrateful, unoriginal, short-tempered and shielded. Except for some grilling during his vice presidential confirmation hearings, he never had to listen to criticism and he is unlikely to have benefited by it.

There were, it's true, flashes of generosity to those who worked for him, but they masked a deeply rooted indifference to the small-scale concerns of others. Rockefeller could manipulate legislators or county chairmen, and play the campaign game in New York's ethnic byways, when he had to. But he did so without enjoyment or awareness of emotional response at ground level. He believed that he "gave" New York a good administration, and wanted to treat the United States to the same largesse. He could not understand dissent or social unrest beyond the cure of expertise. When he bestowed large sums of his own money on public officials, he believed that he was simply helping government to retain top-grade officials who couldn't survive on a civil service salary. He had a tin ear for the distinction between a public stipend and private patronage.

In the end, he was not much unlike the other Rockefellers (and other super-rich with consciences), who believed that if they did Good with their money, it erased the problems inherent in the power attached to the dollars. That he chose to work out this philosophy in the arena of national politics makes his life probably more interesting to study than that of his kinsmen. But of itself it does not lift the suspicion that, except in matters of artistic taste, he had a thoroughly undiscriminating mind.

Persico is openly ambivalent about Rockefeller's qualities, particularly likability. And his court chronicle is not especially good at pursuing implications. Yet he commands attention, and encourages speculations about what a Rockefeller presidency might have held for us (besides many academically glittering blue-ribbon study groups). Rockefeller thought monumentally when it came to preserving the family's visibility. Rockefeller Center rises from the center of Manhattan. The towering Albany Mall complex is now called Rockefeller Plaza. What would we have seen in Washington bearing the great name, and dwarfing the other monuments round about?