He has Parkinson's disease, a congenital, progressive movement disorder. But his vacant stare, characteristic of this syndrome, belies the creative spirit hidden within.

Rosenbaum is an artist — a painter. And his work is becoming an inspiration to other seniors, at the home as well as in the community.

Betty Rothaus, director of the art program at the Home for Jewish Parents, submitted one of his paintings to the "55 & Up, Art for a Lifetime" exhibit at the Bedford Gallery at the Dean Lesher Regional Center for the Arts in Walnut Creek.

Rosenbaum's painting, "Blue and Violet and Gold," was one of 230 accepted into the show. His painting also has the distinction of being one of only four works sold on opening night.

Art has been Rosenbaum's lifelong pursuit. Parkinson's has also been a fact of his life for almost 20 years. Rosenbaum was in his early 40s when the first symptoms appeared. According to Glenna Dowling of UCSF's Parkinson's Clinic, it's more common for the disease to appear in the late 50s or later. But in spite of this, Rosenbaum manages to paint.

"He adapted his painting technique so he could continue to paint at every level of his debilitation," said his son Michael, 35. When his father could no longer paint the clean lines necessary for his mandalas — circular drawings with repeating or geometric designs — Rosenbaum started making mandala collages.

"He used heavy paper stock and an X-acto knife," said Michael. "It scared the living daylights out of me. He had razor blades all around. He wasn't concerned with his personal safety."

Rothaus describes Rosenbaum's current paintings as "abstract with recognizable elements of landscape." She said he paints every chance he gets whether in the art room or his own bedroom.

"I think the current stuff is the best he's done," said Michael, who lives in Berkeley. "It's relaxed and free-flowing. One of his few solid habits was that every day he would paint."

Reflecting on his father's life, Michael said there were few constants during his own youth. He remembers his father changing jobs frequently and estimates that the family moved 20 to 30 times.

His father, who had a degree in engineering physics from Cornell University, worked on the Saturn Missile Project, wrote part of a science text, taught and held other scientific jobs. At home he experimented with color and light. He also wrote and illustrated books for his son Michael and daughter Sarah, 33, who now lives in San Francisco.

Rosenbaum began his artistic career between the Beat and hippie eras. Although he was influenced by both movements, he did not identify with either, his son said.

In the late 1960s, Rosenbaum originated the "light box," a kinetic sculpture that creates a kaleidoscopic effect using cellophane, glass, plastic and principles of light refraction. For years these were sold through a gallery in Los Angeles and found their way into the homes of such luminaries as Ethel Merman, Marlo Thomas and movie director Robert Wise.

Musical instruments were another of Rosenbaum's interests. While working for Creative Playthings in Princeton, N.J., he invented the xylopipes.

"He was one of the first people in the Bay Area to make small wooden talking drums," says Michael. The rectangular wooden boxes had slits in the top for different notes and were played by striking the surface with balls attached to dowels.

Lately Rosenbaum has been painting wooden chairs with brightly colored designs. Functional and decorative, these chairs pepper the art room.

"To have actually worked professionally in both [art and science] is unusual," says Rothaus, who thinks the combination is synergistic. "One area has nourished the other area."

Whatever the reason, the results are satisfying. With financial support from the Solid Gold Ball and physical labor from volunteers like Maurice and Mary Gottlieb who mat and frame paintings, the Home for Jewish Parents is able to host a couple of art shows every year where Rosenbaum's work is prominently displayed.

Although depression and withdrawal are often associated with Parkinson's, according to Dowling, Rosenbaum seems to have escaped such symptoms. He is sociable and well-liked among residents and staff at the home.

He encourages others to participate in the art program and collaborates on art projects like a mobile for the home's Sukkah last year. His paintings hang in the hallways of the home .

Rothaus thinks just having Rosenbaum around brings people into the art program.

"Most of the people in the art program had never painted before," said Rothaus. "John came with his focus intact. He has influenced others. He's very inspiring."