William Rockefeller, the brother of John D. Rockefeller, was not only an energetic and intelligent businessman, he was a man whom people liked. He was open-hearted, jolly, a good storyteller, a man who knew and liked a good horse—not too pious, as some of John’s business associates thought him, bit a man to suspect or fear, as many a man did John.

— The History of the Standard Oil Company by Ida Minerva Tarbell