The first line is the hook. For sure it is not the whole book. But without gaining the attention of the reader with your opening words, the chances are high that your reader may not be interested enough to stay with you the whole way. Hopefully, the first line tells us that we have joined the tale at an intriguing, important moment, and does it in such a way that we absolutely must have further information. 

The following, in no specific order, are the first lines which have stuck in the memory.

“It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.” With the opening of Pride and Prejudice (1813), Jane Austen both sets the scene and whets our appetite for more. A classic start to a classic story.

“It was a bright cold day in April, and the clocks were striking thirteen.” Thirteen? The question in your mind can only be answered by reading further, and so George Orwell’s Nineteen-Eighty Four (1948) will not let you go. Which makes sense, because the book is primarily concerned about thoughts and perception.

“As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect.” Well, that does not happen every day, you say to yourself, as you continue with Metamorphosis (1915), by Franz Kafka.

"The doorknob opened a blue eye and looked at him." Be honest, you are going to copy and paste these words into a search engine, to see if this opening gambit can possibly be true! It comes from short story The Fairy Chessmen (1951) by Lewis Padgett (aka Henry Kuttner). It is also known as The Far Reality.

“Call me Ishmael”. We are captivated immediately, which is the name of the game. From Moby-Dick (1851), by Herman Melville.

“All children, except one, grow up”. Intriguing does not begin to cover these words, with their sinister undercurrent. Which is the start of Peter Pan (1904) by J.M. Barrie.

“It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to heaven, we were all going direct the other way - in short, the period was so far like the present period, that some of its noisiest authorities insisted on its being received, for good or for evil, in the superlative degree of comparison only.” Well, that is A Tale of Two Cities (1859) by Charles Dickens sold to you. All you need do now is to settle down and enjoy the rest.

When all is said and done, no writer wants their book to be judged by the cover. But they cannot argue if the story is judged by the words it contains, however brief the extract that is sampled!