The statue's creator was as industrious as he was gifted. Rodin made several casts of some of his sculptures and often sized them to order for patrons, a standard 19th-century practice. Before he died in 1917, he bequeathed his plaster models and founding rights to the French government. Since then, the Musée Rodin in Paris has occasionally authorized the limited casting of certain works; that is why, for example, there are a few dozen casts of ''The Thinker'' in museums and private collections around the world.

This does not mean that authentic casts of ''The Thinker'' can be purchased just anywhere. As Clare Vincent, a specialist in European sculpture at the Metropolitan Museum of Art, put it, ''They don't come in hundreds by any means.''

But one man, B. Gerald Cantor, did spend many years acquiring the French artist's work, eventually amassing the world's largest private Rodin collection, with more than 750 sculptures, prints and drawings. A co-founder of Cantor Fitzgerald, he used some of the company's office space in the World Trade Center as a Rodin gallery for several years, before donating most of his collection to museums and galleries.

He died in 1996, shortly after a tense settlement with Mr. Lutnick regarding control of the company's future. Despite the internal squabbling, the company's embrace of Rodin continued; the company maintained a small collection of Rodin sculptures, and displayed some of his most famous works in its lobby on the 105th floor of the north tower.

On a limestone pedestal sat a bust of Jean d'Aire from Rodin's ''Burghers of Calais,'' which honored six citizens who, in 1347, yoked themselves together and prepared to die so that their city could be spared the further wrath of an invading English army. In Jean D'Aire's expression, Mr. Tancock said, can be seen myriad emotions: ''Heroism, resignation, strength; dignity in a humiliating situation.''

Also dominating the lobby were ''The Thinker'' and ''The Three Shades,'' both born of a decades-long quest by the artist to complete an ambitious work, ''The Gates of Hell,'' that had been inspired by his reading of Dante, Baudelaire and the Bible. The Adam-like figures in ''The Three Shades'' seem in torment, ''The Thinker'' in almost somber concentration.

These and other works were on display when Flight 11 slammed into the north tower on Sept. 11.

More than two months later, Joan Vita Marotta -- who until 1989 was the curator of the Cantor gallery in the north tower -- was sitting in her suburban Buffalo home, watching a news program about the recovery efforts at Fresh Kills. ''All of a sudden the camera shows a fuselage from one of the airplanes,'' Ms. Marotta recalled. ''And lying next to it is a portion of 'The Shades.' ''