Deep in the Heart of Money : OLD MONEY The Making of America’s Upper Class<i> by Nelson W. Aldrich Jr. (Alfred A. Knopf: $19.95; 297 pp.; 0-394-57036-7) </i>

Insiders who’ve written about America’s ruling class are usually of two types. One includes rebels like Frederick Vanderbilt Field, who described his journey from a Fifth Avenue mansion to the Communist Party in his “From Right to Left,” or Bill Ayers, son of the chief executive of Commonwealth Edison, who penned various manifestoes against corporate America before joining the Weather Underground. The other includes writers like J. P. Marquand or Louis Auchincloss, who have sensitively sketched various corners of the old-money world, but who accept its basic values.

At first glance, Nelson W. Aldrich Jr. seems to fall into the second category. His “Old Money” is dedicated to, among others, his great-grandfather, a U.S. Senator whose small grocery business turned into a $12-million fortune, including a 99-room chateau, thanks to the 30 years he spent doing legislative favors for the Rockefeller and Morgan interests.

And the book ends--oddly, for the author tells us almost nothing of his parents--with the eulogy Aldrich gave at his father’s funeral.

In between, Aldrich’s voice is that of someone in a comfortable leather armchair, telling a story during a long evening over brandy and cigars at an elegant New York or Boston club--a men’s club, definitely, for few women appear in these pages. His narrative meanders leisurely; many characters in it are his own friends or relatives, like Nelson Rockefeller. He draws anecdotes and portraits from interviews, a wide range of memoirs and that classic upper-class gazette, the prep school newsletter:

“One of my St. Paul’s School alumni bulletins . . . contains an intriguing item about Allan MacDougal . . . who was reported to be sailing in the South Pacific aboard his 48-foot German Frers design ketch. He expects to cruise New Zealand waters early in 1987 and then head for Australia, where he may work for a few years. I must confess that my careless Old Money heart lifts in joy whenever I read this sort of notice. I feel reassured that there are still men and women gallant enough and true who dare ask whether some forms of work are better not done at all. . . .”

Do not be deceived, though, by this friendly wave of Aldrich’s cigar. For beneath his almost studied casualness is as thoughtful a psychological portrait of America’s aristocracy as we have.

In one chapter, for example, he brilliantly synthesizes a century and a half of material about how the sons of the rich deliberately put themselves through certain “ordeals” to prove their manhood. One classic ordeal is, of course, war--Teddy Roosevelt on San Juan Hill, Jack Kennedy on PT-109. Another, more carefully controlled ordeal is prep school. And a third is braving nature, where Aldrich shows us the long thread that connects the 19th-Century Wild West journeys of aristocrats Francis Parkman and Owen Wister with William F. Buckley’s celebration of transatlantic yacht racing today. (And, he might have added with heavy upper class patronage, of wilderness survival schools like Outward Bound.)

Aldrich is also a shrewd analyst of ruling class styles in philanthropy. He looks at the vogue for endowing museums, for collecting Old World art, and for preserving New World nature--through the privatized mini-national park systems of patrician organizations like the Maine Islands Preservation Trust or the Nature Conservancy. What all these pursuits have in common is the notion of trusteeship: “Hidden away in the upper class’s special claim to trusteeship,” Aldrich says, “is the secret conviction that the best caretakers of priceless things are priceless people--people who are in some sense the social equals of the things they’ve been charged to preserve.”

Only two things annoy me about “Old Money.” One is that Aldrich’s style is, like a men’s club armchair, a bit overstuffed, abounding with words like catamites, synecdochic, prelapsarian and salvific. He also has a quirky liking for the word invidious and its derivatives, which appear on nearly every page. And he never misses a chance to use Latin, Greek or French-- virtu, tyche, agon, optique, particule-- when plain English would do.

The book’s other flaw is a cavalier vagueness about detail. Aldrich never bothers to tell us how he defines the upper class. How many generations does Money have to be in the family to become Old? Are we talking about 10,000 people or 100,000? And when he casually mentions that Reaganite New Money has taken revenge on Old Money by changing the laws allowing intergenerational trusts, he is wrong. For newly relaxed gift tax laws and absurdly lightened income taxes make it easy for the possessors of both Old and New Money to pass just as much of it on to their children as before.

Such details, however, have never been something the American rich liked to discuss openly. Indeed, one of the few upper class mores Aldrich doesn’t mention is the habit of drawing an artful smoke screen of vagueness over talk of money itself. Is this not a crucial tool that has allowed so much wealth, unearned and untaxed, to be passed down through the generations without the public protest that it deserves?