With his bright sunflowers, searing wheat fields and blazing yellow skies, Vincent van Gogh was fanatic about light. "Oh! that beautiful midsummer sun here," he wrote to the painter Émile Bernard in 1888 from the south of France. "It beats down on one's head, and I haven't the slightest doubt that it makes one crazy. But as I was so to begin with, I only enjoy it."

John White wasn't the most exacting painter that 16th-century England had to offer, or so his watercolors of the New World suggest. His diamondback terrapin has six toes instead of five; one of his native women, the wife of a powerful chief, has two right feet; his study of a scorpion looks cramped and rushed. In historical context, though, these quibbles seem unimportant: no Englishman had ever painted America before. White was burdened with unveiling a whole new realm.

In the late 19th century, the City of Light beckoned Whistler, Sargent, Cassatt and other young artists. As a new exhibition makes clear, what they experienced would transform American art.

In the fall of 1894, the American painter Mary Cassatt attended a dinner in the countryside outside Paris with a group of artists, among them the notoriously bohemian Paul Cézanne. “His manners at first startled me,” she wrote to a friend. “He scrapes his soup plate, then lifts it and pours the remaining drops in the spoon; he even takes his chop in his fingers and pulls the meat from the bone. . . . Yet in spite of the total disregard of the dictionary of manners, he shows a politeness towards us which no other man here would have shown.”

In September 1940, less than three months after Paris had surrendered to Hitler’s armies, artist Henri Matisse, stranded in Nice on the Mediterranean coast, sent a moving letter to his younger son, Pierre, in New York City, explaining why he now needed a model to paint more than ever. France was humiliated and defeated. Like millions of other citizens driven from their homes by the German invaders, Matisse had fled south, taking no more than he could carry, living precariously from one day to the next, and ending up in Nice, where a nervous population expected imminent invasion by Fascist Italian troops.

We don't need Wagner or Tolkien to tell us how powerful rings can be, though it must be said those two make the point pretty convincingly. Most of us have conducted our own ring cycles since childhood. When I was a boy, one of my most prized possessions was a cheap plastic ring, acquired perhaps by mailing in cereal box tops. I want to think that it had some tenuous connection to the effort to defeat the Axis powers late in World War II, a struggle my friends and I desperately wanted to be a part of. I seem to recall the ring had a compartment for secret information, but that may be a trick of my memory. I remember clearly, though, that the ring made me a star among my 7-year-old spies-in-waiting, a status that I hoped to retain with my high-school ring and my college ring, both now as lost, in my case, as the legendary golden trinket forged by Alberich and the Nibelung.

The scene Lautrec stepped into was in the working-class district known as Montmartre, notorious for its thieves and brothels as well as its hangouts for avant-garde artists and literary anarchists. In 1884 Lautrec was a 20-year-old student in the atelier of the painter Fernand Cormon. At the time, the French art world was divided between academic painters like Cormon, who exhibited their work at the Salon des Artistes of the Royal Academy of Painting and Sculpture, and the upstart Impressionists and other radicals, who showed their paintings at the new Salon des Indépendants.