The most influential artist you've probably never heard of Clyfford Still farmworkers art The art of Clyfford Still Clyfford Still, 1951 Clyfford Still letter Clyfford Still, circa 1970s Clyfford Still Museum, Denver Clyfford Still, who died in 1980, is credited with pioneering abstract expressionist art Still walked away from fame at the height of his career in the early 1950s His never-before-seen artwork is featured at a Denver museum The Clyfford Still Museum opened in the fall Denver (CNN) -- Clyfford Still was one of the most influential artists of the 20th century, but it's likely you've never heard of him. That may be starting to change though. More than a half-century after walking away from fame and fortune, the late painter is gaining renewed appreciation, with his work finding a permanent home at a Denver museum. How the Clyfford Still Museum came to exist is nearly as compelling as the paintings on its walls. Still agreed to give away all his art in his possession to an American city that agreed to keep the entire collection intact after his death. He died in 1980. Still is credited with being a pioneer of the abstract impressionist movement in the early 20th century. Yet the breadth of his artistic reach remains a mystery. The museum, which opened in the fall, can only exhibit a small fraction of Still's artwork -- considered the most intact body of work of any major artist. Curators are going through dozens of rolled-up canvases found in his Maryland farmhouse after his widow's death in 2005. These have never before been seen in public. "A lot of the work is just starting to happen now, getting deeper into those paintings and the rolls, doing inventories and learning and trying to understand, if we ever can, what Clyfford Still set out to do," said museum director Dean Sobel. Birth of an artist Born in 1904, Still grew up in rural Washington state and Alberta, Canada. His early work in the 1930s reflects his environment: rugged farmhands and laborers toiling away during the Great Depression. The Clyfford Still Museum opened in Denver last fall after selling four of Still's paintings to help finance construction. His art would quickly begin to morph into a style that would become known as abstract expressionism. "What starts to happen in the later '30s and early '40s is he abstracts those figures and the landscapes they stay in, and he moves closer and closer to his abstract expressionist style," Sobel said. After spending time in California and gaining notice for his increasingly abstract paintings, he moved to the hub of the American art world: New York. There, artists such as Jackson Pollock, Willem de Kooning and Mark Rothko were also moving toward abstraction. "Clyfford Still is among the first to develop an expressionist abstraction and not one that's geometric or hard-edged based on cubes or rectangles," Sobel said. Still's style of abstract expressionism, according to Sobel, showed that "the material of art itself can be expressive as much as the scale and the imagery you include within the painting." By the late 1940s, the art world was beginning to take notice of Still and the new abstract expressionism movement. Collectors began to pay large sums for the paintings, and newspapers and magazines featured large articles on these exciting new painters. Walking away from fame, fortune In 1951, as he was becoming a force in the art world, Still simply dropped out. At the height of his fame, Still withdrew from the commercial art scene to focus on pieces such as "1957-J No. "He writes his dealer at that time and says quite politely and with all respect that he is going to remove himself from the commercial aspect of the art world," Sobel said. In a letter to his agent, Betty Parsons, Still wrote: "Exposing my work (to) a network of associations and evaluations entirely at variance with the implications of my act in painting are brought to bear. I find these not only futile but disturbing in many ways. Still had no intention of giving up on his art: His goal was to focus more on the art and not be distracted or derailed by money and fame. "It's hard for us to understand because now in the 21st century, celebrity and notoriety and I guess the Warholian '15 minutes of fame' we take for granted," Sobel said. But at that time, it surprised many of these artists how much attention they were getting. "When fame and money and careerism enter into the picture, it changes things," he said. Friends become enemies, and I think in the case of Clyfford Still it began to become a negative effect. Still stayed in New York for the rest of the 1950s, and then in 1961 he moved to rural Maryland, where he would live out the rest of his life, painting prolifically but largely out of public view. In Maryland, he painted hundreds of large canvases, plus drawings and pastels while spending time with his children and pursuing his other passions -- cars and baseball. There were occasional gallery exhibitions, including a major show at New York's Museum of Modern Art in 1979 shortly after he was diagnosed with cancer. "There probably was a sense of his own mortality in the late 1970s, and certainly when he did his major exhibition at the Metropolitan Museum in New York, I think he must have known that that would be his last exhibition," Sobel said. Yet Still refused to sell his paintings and became committed to keeping the bulk of his art together. A rebirth Still died in 1980 of colon cancer at age 75. At the time of his death, he was largely a mystery to fans of abstract expressionist art, but he left behind a tantalizing handwritten will that would ensure his legacy in the decades to come. Still was diagnosed with colon cancer in 1978 and died two years later at age 75. "His will is revealed to say that he will give away everything in his possession, which was 94% of everything he ever made, 825 paintings, 1,600 drawings and his complete archive to an American city that will build permanent quarters to house it, show it, take care of it," Sobel said. Before her death, his widow, Patricia Still, chose Denver as the site of the museum. The facility, which opened in November, is housed in a new minimalist modern building in downtown Denver and, as Patricia Still stipulated, it has no auditorium, cafe or gift shop. As curators began to examine Still's paintings at his Maryland farmhouse, they were surprised to find dozens of paintings unceremoniously scattered about the residence. "This was a surprise to all of us, that Mrs. Still was living in and around what were mostly rolled canvases, and probably feeling a bit enshrined in what were 80 huge rolled canvases around her," Sobel said. Decades after his death, Still created a sensation within the art world. In 2011, the museum was authorized to auction four of Still's paintings to help finance construction. The paintings netted a stunning $114 million, with one of the paintings going for more than $61 million. The museum is forcing art historians to re-examine Still and his place in 20th century art, according to art scholar and the museum's adjunct curator, David Anfam. "The revelations of the Clyfford Still Museum's holdings make it clear that the artist easily ranks in the pantheon of abstract expressionists such as Jackson Pollock, Mark Rothko and Willem de Kooning," Anfam said. He said the artwork is also uniquely engaging to the general public. "Even if you know next to nothing about abstract art, I find hard to imagine that anyone could fail to see that they are packed with powerful emotions, ranging from horror to beauty and lyricism," Anfam said. I think he even knew that he would have the last laugh. Dean Sobel, director, Clyfford Still Museum Walking through the galleries, it's hard to believe the works of such a major artist spent so much of his life out of public view. In the end, his legacy may be even larger than the impact of his art alone. "One of the magical things about the Clyfford Still Museum is that sense when you look at the galleries, that most of the material had never been seen before by anyone," Sobel said. Still's decision to keep his artwork intact and reveal it to the public decades after his death is what Sobel called "an example and a model for how you can conduct yourself as an artist." How you can determine your own destiny, how you can create sacrifices for yourself that have larger payoffs later, and even a kind of determination in what you are doing I think has been redefined since Clyfford Still walked this planet. Sobel said. I think he even knew that he would have the last laugh in terms of his contemporaries who had really sold themselves out very early and left very little secrets. Who is a little-known but influential artist to you and why? Let us know in the comments below!