This is the fourth in a series of weekly posts in which I’m going to lay out what I see as some of the building blocks of great fantasy. It’s not gospel, but I hope it’ll help you take a look at your work and find ways to improve it. You can start the series here.

I suppose it’s no great secret that in order to write great fantasy, you need to read a lot of fantasy. I make mention of it here nevertheless because I sometimes catch beginning writers either underestimating or misunderstanding the reading they should be doing.

Reading in the genre is important because your fantasy novel exists in conversation with all the other fantasy novels your reader has read. That’s how the human brain works—it’s always looking for connections between previous experiences and new ones. So if I write gritty, dark military fantasy, it may astonish readers who’ve never heard of Joe Abercrombie, Steven Erikson, Glen Cook, et. al., but I’d better make sure I’m bringing something new to the table for anyone who is familiar with those authors.

And that last point is very important, because there’s a truth about writing fantasy that new authors sometimes miss:

Hardcore genre fans matter more than general readers.

I often hear people just getting into writing fantasy say that they want to write a book that appeals to a general audience. They want everyone to enjoy their books, not just genre fans. They want to write the next Lord of the Rings or A Song of Ice and Fire. That’s a good, noble, and important goal, but it’s putting the cart before the horse.

Your first audience, and therefore your most important audience, is the reader who’s looking for a book like yours. If you write military fantasy, you must impress the military fantasy reader first, so that they will turn to the military historical fiction reader or the high fantasy reader or the general fiction reader and say, “I know you don’t usually read stuff like this, but seriously, this book was so good you have to try it.” If you fail to impress that first reader, the hardcore genre fan, you’re not going to reach the general audience you want to get to. Fantasy works that develop a general audience always develop a genre audience first—even if that genre audience is the acquisitions team at a publisher which then realizes the general-audience potential of the book and works to get it in front of general-fiction readers from day one.

Hopefully that’s established in your mind that you need to read deeply in your genre, but just in case, here’s another reason: readers, whether they’re agents and editors or just the regular kind, will not be enchanted by something they’ve seen before, even if an author hasn’t seen it.

Again, that statement may seem like common sense, but I often find authors just starting their careers ignoring it. Instead they’re afraid that if they read too many books that are like theirs, their imaginations will be squelched and whatever they write will become derivative.

There may be real risk there—I’m far from qualified to speculate about what makes each individual author’s imagination tick—but I will say that all of the successful fantasy authors I know are rabid fantasy readers, and I think there’s a reason for that. If you rehash the quest fantasy or the orphan-who-finds-out-he’s-a-wizard fantasy or the gritty-reimagining-of-the-Hundred-Years-War fantasy while thinking you’re writing something readers have never seen before, you’re in trouble. It’s very dangerous for a reader to start thinking that your book is just like title X, because that’s just one step away from “I’ve seen this before. Meh.” That risk will always exist, because you can’t read everything, but you should do your best to minimize it.

So I offer the following advice: Before you decide to call a book finished, find out whether there’s anything else like it. Take your log line (a one-sentence description of your book—“An orphan boy finds out he’s secretly a wizard and goes to wizarding school” for Harry Potter and the Sorcerer’s Stone) to your local SF/F bookstore, or the library, or a book club, or a Goodreads discussion board, and ask if anyone has read something like that. Then read the novels that come up during the conversation, and make sure that you’re contributing something new to the genre.