Born in Chicago to German parents and orphaned at age nine, Rudolph Weisenborn led a peripatetic life during his youth before settling in Colorado, where he worked as a cowboy and gold miner. In Denver, he enrolled in the Students’ School of Art and studied there for four years under Henry Reed and Jean Mannheim, a German-born, French-trained artist.

Weisenborn followed a traditional academic curriculum, drawing from casts for two years before working with live models. Even as a young artist, he rebelled against the strictures of what he believed to be a stifling approach to art, stating, “It took me ten years to get it out of my system.”

After ten years in Colorado, a visit to an exhibition of impressionist paintings—describ...