Those who’ve heard of Zane Grey usually identify him as the author of best-selling westerns, but few realize that he was the commercially most successful American author of the 1920s. Each year from 1915 to 1924, he had a new novel on the annual list of top-10 bestsellers. Riders of the Purple Sage, The Light of Western Stars, and The Rainbow Trail are still popular, but Grey’s best story may be his own colorful and remarkably little-known life.   Zane Grey was born in Zanesville, Ohio. Grey recalled his own youth as full of relentless conflicts with his stern, demanding father, a farmer’s son who had become a successful dentist in Zanesville. Grey’s delinquency and poor record in school exacerbated matters. Then, midway through his junior year, he had to drop out of high school to help his father who suddenly became poor by pulling teeth for needy locals.   For diversion, Grey played baseball — with enough talent to earn scholarships to several universities. He chose the University of Pennsylvania not only for its accomplished team, but also for its dental school, which offered him immediate admission, sparing him the tough undergraduate program. After graduation, he concentrated more on baseball than dentistry, hoping to reach the major leagues, but to no avail. He retreated to a full-time practice in New York City, but quickly discovered that writing about ancestors whose lives were more distinguished and exciting than his was preferable to coping with decayed teeth and bad breath.   During a summer escape in 1900 to rural Lackawaxen on the upper Delaware River, he met Lina “Dolly” Roth, 11 years younger, a New York doctor’s daughter who enthusiastically supported his yearning to become a writer. After their marriage in 1905, her substantial inheritance enabled him to quit dentistry and write full time. Their cross-country honeymoon trip carried them to the Grand Canyon at the dawn of its tourist appeal. Grey was captivated by the canyon’s natural splendor. He would return there twice more for mountain-lion hunts, which inspired Heritage of the Desert, his first western story, published in 1910 when he was 38. For the next 15 years, he returned annually to the Southwest to find new material for more books.