Anyone who’s taught literature in a college or university lately has probably had a conversation like this. The passion for social justice that many students feel — a beautiful passion for social justice — leads them to be keenly aware of the distasteful opinions held by many writers of earlier generations. When they discover the anti-Semitism of Wharton or Dostoyevsky, the racism of Walt Whitman or Joseph Conrad, the sexism of Ernest Hemingway or Richard Wright, the class snobbery of E. M. Forster or Virginia Woolf, not all of them express their repugnance as dramatically as the student I talked to, but many perform an equivalent exercise, dumping the offending books into a trash basket in their imaginations.

After we moved on from Edith Wharton, we had a pleasant conversation about the different kinds of time machines in fiction and popular culture, from the vaguely described contraption in H. G. Wells’s “The Time Machine” to the tesseract in Madeleine L’Engle’s “A Wrinkle in Time” and the TARDIS in “Doctor Who.”

It was only after the student left the train that I had the rather obvious thought that an old book is a kind of time machine too. And it struck me that the way he’d responded to “The House of Mirth” betrayed a misunderstanding of what kind of time machine an old book is.

I think it’s a general misunderstanding, not just his. It’s as if we imagine an old book to be a time machine that brings the writer to us. We buy a book and take it home, and the writer appears before us, asking to be admitted into our company. If we find that the writer’s views are ethnocentric or sexist or racist, we reject the application, and we bar his or her entry into the present.

As the student had put it, I don’t want anyone like that in my house.

I think we’d all be better readers if we realized that it isn’t the writer who’s the time traveler. It’s the reader. When we pick up an old novel, we’re not bringing the novelist into our world and deciding whether he or she is enlightened enough to belong here; we’re journeying into the novelist’s world and taking a look around.