"Would you like to rest a little?" asked Anthea considerately.
"Yes please," said the Psammead; "and, before we go any further, will you wish something for me?"
"Can't you do wishes for yourself?"
"Of course not," it said... "Just wish, will you, that you may never be able, any of you, to tell anyone a word about Me."
"Why?" asked Jane.
"Why, don't you see, if you told grown-ups I should have no peace of my life. They'd get hold of me, and they wouldn't wish silly things like you do, but real earnest things; and the scientific people would hit on some way of making things last after sunset, as likely as not; and they'd ask for a graduated income tax, and old-age pensions, and manhood suffrage, and free secondary education, and dull things like that; and get them, and keep them, and the whole world would be turned topsy-turvy. Do wish it! Quick!"
This is, I'm told, a pretty famous children's book in England that never really made it across the pond. There's even a movie where the voice of the Psammead--the sand fairy that the five titular children find, and which gives them wishes--is voiced by Eddie Izzard.
Because of that, I was able to approach this book with complete ignorance--which is nice, because nothing else we're reading in my Children's Lit class is unknown to me; most of the texts have been made into countless movies and Saturday morning television shows and lunchboxes and what not. It is a pretty standard be-careful-what-you-wish-for tale, as all the wishes the children make turn sour (e.g., they wish to be "as beautiful as the day" and then their own family fails to recognize them and they get no supper), but it's probably the first modern instance of such a story (it was written in 1904), and ten times as clever as most of them to boot.
Um, guess there's not much else to say about it. Believe in your dreams!