From left, Claribel Cone, Gertrude Stein, and Etta Cone in Fiesole, Italy, in 1903. (The Baltimore Museum of Art/The Baltimore Museum of Art)

Matisse drew them. Gertrude Stein wrote about them. Picasso knew them as frequent visitors to his studio. The Cone sisters of Baltimore may have looked like prim Victorian ladies, with their floor-length skirts and hefty petticoats well into the flapper era, but their tastes in art ran to the avant-garde. Idiosyncratic figures who hobnobbed with modernist masters and made daring life choices, Claribel Cone (1864-1929) and her younger sister Etta (1870-1949) built up one of the most important art collections in American history.

Now a new play is gearing up to pay homage to the siblings: Baltimore playwright Susan McCully's "All She Must Possess" will receive its world premiere at Rep Stage, in Columbia, Md., beginning Feb. 8. The play's characters include Stein, who may have had a love affair with Etta. Also among the dramatis personae: a personification of Matisse's once-reviled 1907 painting "Blue Nude," which Claribel bought in 1926.

Of course, one doesn't have to wait for a play to appreciate the legacy of Claribel and Etta Cone: Their genius still presides at the Baltimore Museum of Art, home to Cone bequests like the "Blue Nude," Paul Gauguin's "Vahine no te vi (Woman of the Mango)" and Picasso's "Mother and Child." Such items, and many more, make the Cone Collection the "crown jewel" of the museum, says the museum's senior curator of European painting and sculpture, Katy Rothkopf.

Claribel and Etta Cone's decision to become avid collectors of modern art was "a very bold and brave choice," Rothkopf observed during an interview in the museum's Cone Wing. Indicating an example of the sisters' daring, the curator lingered near Matisse's "Yellow Pottery From Provence," which Etta bought in Paris in 1906 — a time when Matisse works were still drawing jeers from many viewers. Portions of the still life — most notably a vegetable-heaped plate — are outlined but not painted in, as if unfinished.

"For Baltimore in 1906, this was very radical, very provocative," Rothkopf notes.

The daughters of German-Jewish immigrants, Claribel and Etta grew up in a large family not known for interest in the visual arts. Their father ran a wholesale-grocery operation; their oldest brothers built up a powerhouse textile business. Claribel attended medical school and, at a time when few American women did so, became a doctor. She specialized in pathology, taught, did research in Germany, and wrote papers with titles like "Multiple Hyperplastic Gastric Nodules Associated With Nodular Gastric Tuberculosis." Like Etta, she never married.

Etta's official education wrapped up with high school — just one indication of the sisters' different personalities. Claribel was brasher and more egotistical; Etta shyer and less self-assured.

If Etta seemed diffident socially, her venturesome aesthetic leanings nevertheless emerged at an early age. In 1898, her oldest brother, Moses, supplied her with $300 to use in redecorating the family home: Etta used the money to buy five paintings by American Impressionist Theodore Robinson — possibly the first Impressionist paintings ever seen in Baltimore, Rothkopf says.

The gutsy purchase launched a collection that, thanks to acquisitions principally made during the sisters' frequent trips to Europe, eventually encompassed approximately 3,000 items, including textiles and jewelry. The collection passed to the BMA on Etta's death. Prominent in the trove — testifying to Etta's long friendship with the artist — were 500 Matisse creations, including "Blue Nude." That work had scandalized many earlier in the century: When the watershed 1913 Armory Show traveled to Chicago, for instance, hostile art lovers burned "Blue Nude" in effigy. Yet in 1926, Claribel shelled out for the painting, which depicts a muscular, blue-smudged female body seemingly contorting as she reclines.

Perhaps the vitriol previously showered on the painting even endeared it to Dr. Cone. Both sisters "loved the idea that art provoked thought," Rothkopf says.

How to explain the siblings' ahead-of-the-curve art tastes? Their comfortable incomes — inheritance, supplemented by funds supplied by their textile-magnate brothers — certainly gave them the freedom to pursue their artistic impulses.

Rothkopf points to the influence of the culturally intrepid Gertrude Stein and brother Leo, whom the Cones first knew in Baltimore and subsequently spent time with in Europe. (Leo mentored Etta in art appreciation during her first trip to the continent.)

McCully, the playwright, thinks it's relevant that the Cone sisters never married: As single women, they had time and energy for travel and connoisseurship. "The collection exists in a way because they were, at least, not heteronormative," the playwright theorizes.

An assistant professor at the University of Maryland, Baltimore County, McCully spent a year delving into the Coneses' lives, consulting sources that included the nearly 31 linear feet of the sisters' papers at the BMA. She says she sees Etta as "a kind of gay hero" who succeeded in living life on her own terms, while cementing an extraordinary artistic legacy.

As evidence that Etta was Stein's lover for a time, McCully points to a diary entry of Etta's that alludes elliptically to an encounter (below deck, on an ocean liner) with "the most exquisite qualities of Gertrude." The playwright also notes that Etta had close relationships with other female companions after the intimacy with Stein ebbed.

"All She Must Possess" (which is part of the 2018 Women's Voices Theater Festival) is not the first play to recall Claribel and Etta Cone: "The Cone Sister," written by Naomi Greenberg-Slovin as a solo vehicle for her own sister, Baltimore actress Vivienne Shub, proved wildly successful at Baltimore's Everyman Theatre in 2006 and 2007.

It is no accident that both plays have cropped up in the Baltimore area. There is "an affinity and love for [the Cone sisters] in our region," says Rep Stage's Producing Artistic Director Joseph Ritsch, who directs "All She Must Possess."

Who can wonder? The sisters "had a huge impact on the interest in modern art in the city," says Rothkopf.

All She Must Possess, Feb. 8-25 at Rep Stage at the Horowitz Visual and Performing Arts Center at Howard Community College, 10901 Little Patuxent Pkwy., Columbia, Md. Tickets: $10-40. Call 443-518-1500 or visit repstage.org.