Rather than giving us license to write about what we don’t know, Henry James wants us to understand that the notion of experience is complicated. “The power to guess the unseen from the seen, to trace the implication of things, to judge the whole piece by the pattern, the condition of feeling life in general so completely that you are well on your way to knowing any particular corner of it—this cluster of gifts may almost be said to constitute experience.” James astutely shifts the focus from the quantity of experience to the quality of experience by urging the writer, “Try to be one of the people on whom nothing is lost!”
That phrase deserves particular reflection. It recognizes that for writers experience is ultimately internal. A person may have worked on the railroad for forty years, traveled to exotic countries, or had a galaxy of escapades, but if that person is not observant, perceptive, and thoughtful about those experiences, that will show itself in the writing. On the other hand, if you have paid close attention, ideas for fiction will occur within the smallest compass. Educating yourself to be one of the people on whom nothing is lost is the deepest experience of all.