As the chief curator of the Royal Academy of Art in London, Rosenthal has overseen such watershed shows as "Sensation" and "Apocalypse" (young British art, chapters one and two) as well as the critically acclaimed blockbuster "The Genius of Rome" (Caravaggio and the birth of the Baroque between 1592 and 1623) and, currently, the "Return of the Buddha," which displays for the first time in the West an extraordinary cache of sixth-century Chinese sculptures.
Rosenthal knows his way around the art world, literally and figuratively, and no one in today's ad hoc group -- on a layover before the Documenta and Basel art fairs -- disputes Rosenthal's right to lead this tour of "the new thing to see in Berlin," as he describes the Alte Nationalgalerie.
He briefly consults a map -- and then disregards it.
"Let's have a look at some sculpture to get the overall impression," he suggests steering his charges toward a ground-floor gallery of cool classicist sculptures. "It's all about the overall impression."
But having said that, Rosenthal singles out a statue of an amorous couple who appear to be carved from a block of virgin snow.
"Is it Schadow?" he surmises, peering at the plinth through half glasses to confirm the artist and teasing the others, "I'm sure you recognized it." (Johann Gottfried Schadow, 1764-1850).
From there, Rosenthal sets out at a fierce clip. He's dressed like a housepainter, but speaks like a lord -- charming and slightly wicked -- and he comments on everything he sees. Nineteenth-century easel painting might be an academic subject, but on Rosenthal's tongue, it sounds as fascinating as cocktail-party gossip.
"Did you know Boldini painted Menzel?" he asks provocatively in front of Giovanni Boldini's portrait of German Realist painter Adolphe Menzel. He answers himself by adding a biographical fact not apparent in the portrait. "Menzel was a dwarf, or at least a very little man."
As for Menzel's talent as an artist, Rosenthal says, "you don't know whether he is great or not. But some of his works do have something." A portrait of the artist's foot, for example, draws praise, as does a famous interior ("The Balcony Room") said to prefigure Degas.
From painting to painting, Rosenthal's museum sprint doesn't allow much time for careful scrutiny, but for a nonprofessional visitor, that hardly matters. It must be admitted that the actual collections, all 19th-century Romantic Sturm und Drang or idealized pastoral fantasies, appeal to fairly specialized tastes. "I could whiz right past it," one of Rosenthal's group admits.
On the other hand, the building itself, styled as a Greek temple outside, shows the most elegant side of 19th-century decorative arts. It's an active pleasure to walk across the dark parquet floors and drink in the pale blue plaster walls, the gold leaf moldings and the red marble columns topped with Corinthian capitals. It forms the perfect context for all those pseudo-Hellenic nudes and stormy mountain vistas, souvenirs of the 19th century and its contradictions -- an era both spiritual and disciplined, prosperous and educated.
Or, to go back to Rosenthal's idea of the "overall impression," one word will suffice.
"It's fabulous," says the curator, running a respectful hand along one of the fresh walls. "Fabulous.""