There's been a lot of talk recently about author Meg Rosoff's comments that good literature "does not have the 'job' of being a mirror." Rosoff argued that there are already "thousands" of books for marginalized youth, and people shouldn't put in any effort to feature diverse protagonists, because good literature is about expanding your mind, and should speak to many people. In the terms most commonly used online, she's arguing that books should be windows, not mirrors -- they should let readers see and experience new things, and not just allow them to be exist in a comfortable space where they see themselves.
Her arguments have been disputed many times at this point by people far more eloquent than me, so I won't get into it here, except to ask "a mirror for whom?" "Good literature" typically features straight, white protagonists, providing a mirror to all straight white readers out there. Are people really arguing that other readers should be happy to read those books as a window into another perspective, but that straight white readers shouldn't be expected to do the same?
Stories cannot be separated into "windows" and "mirrors," where some show readers new worlds, and some just show them what they already know. Every reader has different experiences and perspectives, so a "mirror" for one is a "window" for another, and no book is 100% window or mirror for anyone. No book character is identical to the reader, and no book character is so completely different to the reader that they cannot see themselves or empathize with them at all.
"Window" implies a barrier between the reader and the character -- the reader is watching the character, but there's total separation. Yet reading is an interactive experience. Yes, a lot of fiction is about exploring things the reader will never see or experience themselves, but the heart of fiction is more often than not about exploring things that readers do experience -- hope, determination, heartbreak, fear. Human nature and all its strengths and pitfalls. Even the most fantastical fantasy or science fiction novel is grounded in the strengths, flaws, quirks and emotions that we see in the people around us, and see in ourself.
Similarly, no book is 100% a mirror. There will always be differences, and those differences can open the reader up to new possibilities, and help them to see things about themselves. Rosoff argued that books are "to teach kids about the world, about being different or being brave," and the books that do this best are the books that provide at least some form of mirror for the reader. These books don't just provide the comfort of seeing a character who is like the reader, but also the inspiration of seeing what a person like that can do. It's fortifying and inspiring to see a character like yourself be brave and conquer their problems and fight literal demons and save the world... or at least survive high school and figure out their lives.
And let's be honest -- most books are that kind of "window" for straight, white readers, especially straight, white, cis male readers. Some people may just see those characters as the "default," but they provide constant mirrors, and constant windows into potential and opportunity, for these particular readers. Why, then, is it so controversial and anti-literature to change up the formula, so that "marginalized youth," as Rosoff said, can experience this too? Every book is a different mix of window and mirror for every single reader, and every single reader deserves books that challenge their own perspectives and their sense of normal, but also books that reassures them about themselves and show them what they could be.