When Mort Walker (1923-2018) was ten years old, he received an inscribed Moon Mullins cartoon from its creator Frank Willard that read, "Say Morton, those drawings you sent me were swell--I'll bet you'll be a big-shot cartoonist someday." By the time he was fifteen, Walker was a comic strip artist for a daily metropolitan newspaper. By the time he was eighteen, he was chief editor of Hallmark Cards. In 1950, King Features picked up his strip...