Robinson claimed that it was his 1940 card sketch that served as the character's concept, and which Finger associated with Veidt's portrayal. Kane hired the 17-year-old Robinson as an assistant in 1939, after he saw Robinson in a white jacket decorated with his own illustrations. Beginning as a letterer and background inker, Robinson quickly became primary artist for the newly created Batman comic book series. In a 1975 interview in The Amazing World of DC Comics, Robinson said he wanted a supreme arch-villain who could test Batman, not a typical crime lord or gangster designed to be easily disposed of. He wanted an exotic, enduring character as an ongoing source of conflict for Batman (similar to the relationship between Sherlock Holmes and Professor Moriarty), designing a diabolically sinister-but-clownish villain. Robinson was intrigued by villains; his studies at Columbia University taught him that some characters are made up of contradictions, leading to the Joker's sense of humor. He said that the name came first, followed by an image of a playing card from a deck he often had at hand: "I wanted somebody visually exciting. I wanted somebody that would make an indelible impression, would be bizarre, would be memorable like the Hunchback of Notre Dame or any other villains that had unique physical characters. " He told Finger about his concept by telephone, later providing sketches of the character and images of what would become his iconic Joker playing-card design. Finger thought the concept was incomplete, providing the image of Veidt with a ghastly, permanent rictus grin.