Robertson Davies, Canadian novelist, playwright and essayist, plans to concentrate on Thomas Mann and George Bernard Shaw when he speaks Sunday at Johns Hopkins on "Creativity in Old Age," but he offers a fine example of his topic himself. Mr. Davies, who lives about 50 miles outside Toronto, turned 80 in August but still maintains an on-the-go work schedule. The first of his 30 books was published in 1939, his most recent novel in 1991. "The Deptford Trilogy" is one of his best-known works. And he maintains an active speaking schedule as well. "Some people come into their best energy after middle age, others when they are quite young," Mr. Davies says. He says he focuses on author Mann and playwright Shaw because old age stopped neither. "Shaw lived until age 94 and he worked until he died," he says. "He didn't get going until he was in his 40s. His play, 'Too True to be Good,' was written when he was almost 80. "Mann had early success as a novelist, by age 25. He was active until the end. He died at 80." Mr. Davies is one of four keynote speakers for a symposium titled "A View of Winter: The Art of Growing Old" that will be held at the Turner Auditorium of Johns Hopkins Medical Institutions. The three-hour event is sponsored by the medical institution's Office of Cultural Affairs. Christin C. Goodell, symposium coordinator, says the title addresses the "dialogue between the triumphs of the spirit and the inevitable demands of the failing body." Other speakers are social historian Lois Banner, author of "In Full Flower: Aging Women, Power and Sexuality"; art historian David Rosand, on "The Old Man's Brush," and Dr. Christine Cassel, to discuss "Successful Aging: Myth or Promise." Dr. Cassel will provide the ethical "bridge between humanistic perspectives and . . . socio-medical concerns." Turner Auditorium is at 720 N. Rutland Ave. Tickets are $5. Free parking is available at one garage. For information, call 955-3363.