“Write me a story,” I said to the girls in my junior high composition class. “It is due next Wednesday.”

That was the extent of the assignment I gave them. No limits, no rules, no guidance—nothing. Admittedly, I was new—as a first-year teacher, I had no way of knowing what I was in for or how grave an error I had just made. If I had been more experienced, I would have been alarmed by the eager light coming on in the students’ eyes. These were aspiring writers, after all. They had always wanted to change the world with the great American novel, and I had just promised to edit it for them.

Each of them.

When Wednesday finally came, the students marched proudly to the front of the room and placed their stories on my desk. As the stack mounted, my heart sank into my shoes. The overwhelming mass of paper in front of me would take three weeks to read. Then and there, I firmly resolved never to make such a foolish assignment again.

It turns out I needn’t have worried. The task was much easier than I had feared, primarily because all of the stories were more or less identical. The main storyline of each and every one of them went something like this:

Once upon a time, there was a beautiful princess. She lived in a beautiful kingdom far away, where she was the beautiful daughter of a beautiful king and his beautiful queen. She grew up with every possible advantage and lived a beautiful life of delirious happiness, eventually growing up to be a beautiful young woman. And just when her beauty was at its most beautiful, a handsome prince came along on a beautiful white steed and swept her up into his strong arms. He made her his queen and carried her off to an even more beautiful kingdom, where she lived in Elysian rapture to a ripe old age and finally died of bliss. The End.

Though I just about died of an overdose of Elysian rapture before the job was done, I managed to read all the papers. The next day the students and I had an important conversation, not only about writing stories but also about reading them.

The stories, I explained, all suffered from the same problem: lack of a problem. The protagonist princesses, bless their hearts, didn’t face difficulties or obstacles of any kind. You left out the cruel stepmother, I said, and the omission was fatal. Since nothing bad ever happens to the princess her story fails to arouse even the mildest interest on the part of the reader. Nothing improves a story like a good disaster, I told them. Remember that.

It turns out, of course, that the lesson my students learned that day is as powerful a tool for reading stories as it is for writing them. As readers, our most important task is to identify and understand the central problem—the conflict—in a story. This is the first step toward understanding the story as a whole.

The conflict of any story is the disagreement at the root of things: the competition for the prize, the obstacle between the protagonist and his goal, the misunderstanding that must be worked out. As my students learned, conflict is the most essential ingredient in any story; without it, there’s really no story to tell.

Though there are as many specific conflicts as there are stories in the world, they may be grouped into five simple categories:

1. First, there is a “man against man” conflict. This conflict exists when the main character, or protagonist, struggles against another character, the antagonist, in pursuit of his goal. We might also say that a “man against man” conflict exists when the primary antagonist is a person. Just about every fairy tale with a wicked stepmother or a cruel sorcerer has a “man against man” conflict, as do stories like Stevenson’s Treasure Island (Jim Hawkins vs. Long John Silver) and Richard Adams’ Watership Down (Hazel vs. Woundwort).