There are almost always elements of egocentricity and unseemly acquisitiveness in art collecting, and the study of the field can easily become a species of what Tom Wolfe once called “plutography.” But one of the most interesting phenomena in Western culture is the two-century-long (and counting) transoceanic movement of the world’s artworks from Europe to American cities as diverse as New York and Toledo. The phenomenon, which had already achieved epic dimensions by the late 19th century, is unprecedented in history. Yes, the British claimed their imperial booty, as did other European nations in the age of empire. But for decades, the Port of New York admitted on a daily basis ships stocked with wooden crates containing Old Master paintings, Chinese pots, Greek vases, medieval statuary, as well as architectural fittings, furniture, stained-glass windows, whole disassembled interiors, and even whole buildings.

Most of us, when we read of collectors’ plutographic exploits, tend to focus on names such as Morgan, Frick, and Rockefeller, or the countless collectors dazzled and sometimes defrauded by buccaneering international dealers such as Joseph Duveen. But not every collector was a tycoon or a swindler. The first of many virtues of James Stourton’s book “Great Collectors of Our Time: Art Collecting Since 1945” (Scala, 416 pages, $85) is that it encyclopedically brings us up to date on the state of collecting. There is more than enough here to satisfy anyone’s plutographic leanings. But the detail Mr. Stourton provides is unexampled in giving us a view of the differing motives of collectors.

The book isn’t about just American collectors — though they do stand out. Seven sections cover collectors in Paris, America, Switzerland, Germany, Asia, London, and the rest of Europe. Each section is subdivided into subsections — “Chicago Collectors,” “Picasso’s English Friends,” etc. Then, each of these is subdivided into encyclopedic entries. Thus, in “America Triumphant,” the subsection “The Grand Possessors” comprises entries on Paul and Bunny Mellon, Charles and Jayne Wrightsman, the Rockefeller family, and John Hay Whitney. Each of the entries includes splendid illustrations. For Nelson Rockefeller, there’s a color photograph of the music room at Kykuit, in Pocantico Hills, N.Y., in which a reproduction of Joan Miró’s “Hirondelle d’amour” (1934) coexists in surprising harmony with Ogden Codman Jr.’s superb moldings. In the section on the Wrightsmans, we find a reproduction of David’s portrait of the Lavoisiers, in my opinion the finest French painting in the Metropolitan Museum of Art and alone a worthy enough legacy for any collector to leave.

But of course the Wrightsmans didn’t leave it at that. Especially in this season, which has seen the eagerly awaited reopening of the Met’s Wrightsman Galleries of French Decorative Arts, I was drawn first to their entry in Mr. Stourton’s book. (I can’t imagine anyone reading this book from start to finish; rather, I can imagine grazing through it or, even more probable, keeping it close at hand as an essential reference.) The Wrightsmans are excellent examples of public-spirited collectors. Mr. Stourton notes that Francophilic American collectors — Louisine Havemeyer, Chester Dale, etc. — of the first half of the 20th century were besotted with Impressionism.

The Wrightsmans began with Impressionism, but their destiny lay in the century before, and they became the most serious collectors in American history of the French ancien régime. It began as a personal preference and developed into something of a mission, which was to express itself in the glorious series of Wrightsman rooms at the Metropolitan Museum in New York.

Mr. Stourton, who is the chairman of Sotheby’s UK, knows his subjects intimately, and his entries are filled with lovely anecdotes. Mrs. Wrightsman and Bernard Berenson became close friends in the early 1950s. The elderly Berenson despaired of ever seeing the National Gallery of Art in Washington, D.C., which was a monument not just to the Mellon taste (and fortune), but to the Berenson touch in attributing and advising. The Wrightsmans then photographed the entire museum themselves for Berenson’s enjoyment. Such stories abound in “Great Collectors of Our Time,” which, for the quality of its information, the conversational tone of its prose, the worldwide breadth of its coverage, the perfect length of its entries (not too short, not too long), and its marvelous illustrations is as good as one could ever hope such a book to be. Not least, it’s a much-needed book, as I know no other like it.