In the mid-’90s, not long after I graduated from college, a friend insisted I read “The Manual,” by the Roman Stoic philosopher Epictetus. For an ungainly introvert like myself, the book’s premise was irresistible: Epictetus had written a how-to-adult handbook — a literal manual for being a human! — in sentences rebarred with moral certainty. “Of things some are in our power, and others are not,” he contends in the first line. “Wish the things which happen to be as they are, and you will have a tranquil flow of life.” Epictetus didn’t make the world more sensible and ordered, exactly, but suggested that our responses to it could be.