What makes a book captivating? One might say a bold hero, a beautiful heroine, a thrilling plot, or a dastardly villain. But before the prince saves the princess, what happens? What happened before the two lovers we reunited? How did the story begin? With the first sentence, you set the tone of a story. It changes the atmosphere of the book, and with it, you start to descend into that world.
If you have the wrong first sentence, you ruin the whole book. A horror story, does not begin talking about cute furry animals. A fairy tale shouldn't start with death. But how do you start it? As modern society dictates, fairy tales begin with dreamy beginnings. Once upon a time....The princess started longingly out of her castle window...that stuff.
So to set an example of the effect of first sentences, lets observe a few from famous books.
"First of all, let me get something straight: This is a JOURNAL, not a diary. -Diary of A Wimpy Kid, by Jeff Kinney
This sets the tone of the book. It shows that the point of view is from a young person, probably male considering they absolutely detest the idea of a *shudder* diary. The lighthearted words show it's not going to be a hugely serious story. Now contrast it to my next example.
"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want for a wife." -Pride and Prejudice, by Jane Austen
The sentence reflects maturity and intelligence, and you know that this isn't a silly, funny story. The implications set the tone of a possibly imminent marriage, but you know in an instant that the story is a romance.
"You want a fairy tale, don't you? Well I'm not sure i can give you that." -The Fire, book three in the Witch and Wizard series, James Patterson.
Of course, this is another great book- famous too. What can you learn from these two simple sentences? It isn't a necessarily happy story, hardship is plausible. And you know by the mannerisms, that this in a first person perspective who is young, definitely not an adult.
By now you should understand how crucial the first sentence is. So, you may ask, how do make a killer first sentence? Think, what is your story going to be about? In some respect, a prologue could accomplish as much. But any sentence has to characterize your story.
So don't just write off the top of your head every time- think it through. And the right sentence will come to you.