Edison's best-known adage appears in various forms, the shortest being his comments to an interviewer that "genius is one percent inspiration and 99 percent perspiration," his reply to a question about genius from Samuel Insull. For some years his secretary, more accurately reflects what he really thought: "Well, about 99 percent of it is a knowledge of the things that will not work. The other one percent may be genius, but the only way that I know to accomplish anything is everlastingly to keep working with patient observation."