During the Franco-Prussian war, [Renoir] was drafted into the cavalry and found that he was a natural with horses. The secret, he said, was to treat them as he did his [artist's] models.
He let them do exactly as they pleased, and soon they were willing to do anything he wanted.
In «Suffering for their art», a review by John Carey of Sue Roe's «The Private Lives of the Impressionists» in the Times Online
Haven't decided whether I'm repulsed or fascinated by this observation -- but I think I'm leaning towards fascinated.