Walt is said to have drawn the first sketches of Mickey Mouse on a train to Los Angeles after losing the rights to Oswald, the cartoon rabbit. Viewed from a distance of over 70 years, it appears that Mickey's success was inevitable, that he was a kind of force of nature in entertainment, destined to become one of the most beloved characters in the world. But the truth isn't so simple. In fact, Mickey Mouse could easily have become just another character in the history of animation, joining the likes of Popeye, Betty Boop, and Felix the Cat. In fact, when Mickey was first created he didn't look so very different from many of his predecessors. Clearly, the most significant factor that led to Mickey's super-stardom was his optimistic, cheerful, resilient character -- one very much like Walt's. It may be true that animator Ub Iwerks was largely responsible for Mickey's final form -- reworking Walt's sketches to make the mouse easier to animate. But as old animators have commented, according to animation historian Charles Solomon, "Ub designed Mickey's physical appearance, but Walt gave him his soul."