In 1949, while Henri Matisse (1869-1954) was still in the South of France cutting shapes out of colored paper, Etta Cone from Baltimore gave 600 of his works to the Baltimore Museum of Art. Over the years, those 600 were complemented by 600 more, many acquired by the Baltimore museum from Matisse’s family.

All that adds up to a lot of Matisse.

The BMA’s holdings are not, of course, the only reason that great works by Matisse are easier to find in America than in the artist’s native France. Albert Barnes from Philadelphia, Sarah and Michael Stein from San Francisco, and Alfred Barr from New York all played significant roles in that happy state of affairs. But the sheer number of works at the BMA and their quality means that for any Matisse lover, a pilgrimage to that city has always been obligatory.

That is more the case in 2021 than ever. On Dec. 12, the museum will open a Matisse research center — the Ruth R. Marder Center for Matisse Studies. Hosting conferences and driving publications, the center will include a dedicated exhibition space, a library and a study room. Ahead of that launch, the BMA has mounted a marvelous Matisse exhibition that offers a fresh perspective on its own rich holdings. The show, organized by Leslie Cozzi and Katy Rothkopf, is called “A Modern Influence: Henri Matisse, Etta Cone, and Baltimore” and runs through Jan. 2.

Perhaps the most notable thing about the title is the absence of any mention of Etta’s sister, Claribel, as both sisters were important to the formation of the collection. But Etta, who was long overshadowed by her older, more brilliant and outgoing sister, ultimately played the more significant role. This show is the first full-throated attempt to acknowledge that.

The Cone sisters were the daughters of German Jewish immigrants who had a thriving grocery business in Tennessee. The family moved to Baltimore, where their brothers became wealthy manufacturing textiles. They shared their wealth with their sisters. Claribel studied at the Women’s Medical College; Etta played piano and managed the family household.

They began traveling to Europe together in 1901, and first saw works by Matisse in the company of Claribel’s friend Gertrude Stein (who described them in her poem “Two Women”) at the 1905 Salon d’Automne in Paris. That exhibition contained a room — the notorious Salle VII — filled with crude, brightly colored paintings by Matisse and his rebel friends — the “Fauves,” or “wild beasts,” as one critic called them. Fauvism would become the first major avant-garde movement of the 20th century.

“We asked ourselves,” wrote Claribel, “are these things to be taken seriously?” For most of Matisse’s compatriots, the answer was no. Matisse’s most important collectors were all foreigners — mostly American and Russian, some Jewish. What did they see in Matisse’s radical early work that the French could not?

In her great Matisse biography, Hilary Spurling provided one resonant answer. When Sarah Stein, Gertrude’s sister-in-law, moved to Paris, Spurling wrote, “she brought with her the gift of the New World to the Old: voracious, semistarved cultural appetites, freedom from an enfeebled and contaminated tradition, the native vigor of a rootless race of outsiders accustomed from earliest years to consult and act on their own powerful intuitive response.”

Much of this could also apply to Etta and Claribel Cone. During the winter of 1905-06, Etta lived in an apartment on the rue Madame near Paris’s Luxembourg Gardens, immediately above Sarah and Michael Stein, who were family friends. Claribel, a physician, was conducting pathological research in Germany, and would visit Paris whenever she could.

Sarah took Etta to Matisse’s Paris studio in 1906, just as the artist was getting embroiled in an intense competition for leadership of Paris’s avant-garde with a young Spaniard named Pablo Picasso. The most explosive salvo in that burgeoning rivalry was Matisse’s “Blue Nude (Memory of Biskra),” which Claribel ended up purchasing from Gertrude Stein and her brother Leo. Inspired by Matisse’s recent trip to North Africa, the painting showed a reclining woman against a roughly painted background of spreading palms.

Put that way, it sounds lovely. But to people who saw it at the time — and still to many today — it was incomprehensible, ugly and raw. Using the blue-green palette of his beloved Cézanne, Matisse had distorted the figure’s form in an early effort to achieve what he spent the rest of his life trying to perfect: dispersing sensation in waves across the entire picture. Where later in his career Matisse would emphasize an appearance of effortlessness, here he wanted to show the strenuous intensity of the work that went into making the “Blue Nude.” Zoom in on the figure’s right shoulder, for instance: It looks completely butchered.

“Blue Nude” — which isn’t in the new BMA show but is on display in the Cone Collection galleries downstairs — was mocked and reviled by critics and the public alike. To almost everyone who saw it, including Picasso, it was a failure. But Picasso was haunted by it. He sensed Matisse was onto something and it drove him half-crazy. His attempt to understand and surpass what Matisse had done in “Blue Nude” led to his own breakthrough painting, “Les Demoiselles d’Avignon,” later that year.

In any case, the Cone sisters’ early encounters with Matisse planted a seed. Etta purchased two drawings after her first visit to his studio, then two more works on paper and a painting. But it wasn’t until the 1920s that the sisters began collecting in earnest. By this time Matisse had moved to Nice, France and was painting smaller, far less confronting works.

When, in 1929, Claribel died unexpectedly, Etta was devastated. She was 60 years old. All her life, she had been living in Claribel’s shadow. She was at a loss about how to continue with her own life.

In Claribel’s day, according to Spurling, “the Cones’ purchases had been abundant, careless, and largely random.” Claribel “didn’t even realize she had a collection until the time came to make provisions for it in her will.” This now changed. The collection “gave Etta’s life meaning and purpose, and offered freedom from convention,” according to BMA Director Chris Bedford.

Matisse felt a personal connection with Etta, and in 1930 he came to visit her in Baltimore. He had traveled to America the previous year and it had been difficult. His face had appeared on the cover of Time magazine and he was feted at the White House, but the trip was hard work. The heat and humidity were close to unbearable. “Cocktail parties and banquets all the time — Americans are all alcoholics,” he complained to his wife. Albert Barnes, a keen-eyed collector but notorious bully who had commissioned Matisse to decorate the central hall of his new museum in Merion, Pa., was going to be tricky to work with. And the economy was crashing.

Etta’s modest manner and her evident sincerity provided an antidote to all this. Near the end of 1930, as he stepped into her apartment, wrote Spurling, Matisse was “surrounded by his pictures, hanging everywhere including the bathroom and the bedroom, their power and sensuality intensified at close quarters in these small, dark, cluttered spaces.” He was overwhelmed — and deeply moved. The meeting produced a collaboration that, as Spurling wrote, “would outlast them both, and prove in that respect more valuable to Matisse than any other relationship he ever had with a collector.”

It’s not clear whether Cone was a lesbian, but she certainly loved Matisse’s drawings of women, which are fired with a sensuality that, by admitting reality, feels authentically intimate, and less like the projection of a male fantasist. The poet Louis Aragon (quoted in the show’s catalogue) wrote that the most mysterious thing about Matisse was that he understood “better than anyone else the way fabric lies against flesh, and how the straps and ribbons cross and slip in a woman’s garments, how they wind about her waist or close to her armpit or under the curve of her breast: so many secrets that are not to be found in any dictionary.”

Among the show’s most captivating works are a 1929-31 painting, “The Yellow Dress,” which eludes my ability to find apt words but absolutely epitomizes Matisse’s genius as a colorist; “Purple Robe and Anemones,” a 1937 painting of almost impossible suaveness; and the illustrations he made for a 1932 edition of Stephane Mallarmé’s poems — the first of many books he would illustrate.

The exhibition is especially rich in works from the artist’s Nice period, when he painted hotel interiors, models dressed as odalisques against busy decorative backdrops, and coastal landscapes. Matisse’s touch and his orchestration of complex color harmonies in these deceptive pictures are riveting. You can feel how much he was looking back to Manet — and to a lesser extent Monet and Renoir. The mood of gentle eroticism and playacting has an 18th-century sweetness, as in the decorations of Boucher or Fragonard. But as always in Matisse, you can feel something brewing — a tension, a sense of feeling so heightened that you intuit it will take all of Matisse’s disinterested and self-abnegating intelligence to master.

That tension is visible again in the distortions Matisse began to reintroduce in the 1930s, and perhaps especially in his great “Large Reclining Nude” — sometimes called “The Pink Nude” — of 1935. The painting’s sensuality is much more smoothly sublimated than in “Blue Nude” 20 years earlier. Its forms are if anything weirder. But Matisse’s distortions had such a quality of rightness by this stage of his career that they lodge effortlessly in the mind. The painting went through many iterations and took six months to complete, but you feel you could copy it in about 20 minutes.

I don’t know whether to call Matisse’s process distillation, sublimation or some other term. (It’s not idealization; Matisse loved reality too much to fall for the chimera of perfection). But I do know that it’s the opposite of the principle of arbitrariness embraced by Picasso. A lot of life is arbitrary, so I’m not faulting Picasso. I am just thanking Matisse, along with his friend and champion Etta Cone.

A Modern Influence: Henri Matisse, Etta Cone, and Baltimore Through Jan. 2 at the Baltimore Museum of Art.