The Voyage of the Dawn Treader
How we cite our quotes:
It would be nice, and fairly nearly true, to say that "from that time forth Eustace was a different boy." To be strictly accurate, he began to be a different boy. He had relapses. There were still many days when he could be very tiresome. But most of those I shall not notice. The cure had begun. (7.61)
The narrator doesn't ask us to believe that Eustace changed overnight – he makes it clear that personal transformation is a gradual process that happens in fits and starts.
"That water turns things into gold. It turned the spear into gold, that's why it got so heavy. And it was just lapping against my feet (it's a good thing I wasn't barefoot) and it turned the toe-caps into gold. And that poor fellow on the bottom – well, you see." (8.71)
Perhaps what makes the gold on Goldwater Island more appealing than regular deposits of gold in mines is that it's so easy to obtain. Anything can turn to gold, instantly, without any apparent price or sacrifice.
"The king who owned this island," said Caspian slowly, and his face flushed as he spoke, "would soon be the richest of all kings of the world. I claim this land for ever as a Narnian possession. It shall be called Goldwater Island. And I bind all of you to secrecy. No one must know of this. Not even Drinian – on pain of death, do you hear?"
"Who are you talking to?" said Edmund. "I'm no subject of yours. If anything it's the other way round. I am one of the four ancient sovereigns of Narnia and you are under allegiance to the High King my brother."
"So it has come to that, King Edmund, has it?" said Caspian, laying his hand on his sword-hilt. (8.78-80)
The Midas-like transformation of everything into gold on Goldwater Island also causes another, more sinister transformation: Caspian and Edmund are almost instantaneously turned into greedy enemies.