In “The Art of Fiction,” Henry James gave the example of an English novelist who was asked how she was able to depict the lives of French Protestant youth so vividly and true to life. Her response was that it all boiled down to once looking into a room:

Once, in Paris, as she ascended a staircase, [she] passed an open door where, in the household of a pasteur, some of the young Protestants were seated at table round a finished meal. The glimpse made a picture; it lasted only a moment, but that moment was experience. She had got her impression, and she evolved her type. She knew what youth was, and what Protestantism; she also had the advantage of having seen what it was to be French; so that she converted these ideas into a concrete image and produced a reality…

James uses this example to argue that experience is crucial to writing but that experience can be just about anything. Even a glance. In short:

Try to be one of the people on whom nothing is lost!