I've always wondered if Jack London took on his many and diverse experiences for their own sake, or because of the fodder they would provide for subsequent novels. I think the latter, hence "the method writer," one who has to experience before he can write about something.
Earle Labor has long been a devotee of London, so one expects a largely sympathetic biography, although the short description says "not uncritical." London's energy appeared boundless, and he took great interest a great number of causes, notably the Bolshevik Revolution in Russia. He was a major proponent of labor reform in America, which ran him at odds with establishment views. No matter, Jack was an iconoclast if nothing else, and role model to many writers who followed in his wake.