"Do you want to go into the crystal cave again?"
"N-no, I don't. But I think perhaps I should. Surely you can tell me that?"
He said heavily, after a few moments: "I think you must go in, yes. But first, I must teach you something more. You must make the fire for yourself this time. Not like that—" smiling, as I reached for a branch to stir the embers. "Put that down. You asked me before you went away to show you something real. This is all I have left to show you. I hadn't realized... Well, let that go. It's time. No, sit still, you have no more need of books, child. Watch now."
Of the next thing, I shall not write. It was all the art he taught me, apart from certain tricks of healing. But as I have said, it was the first magic to come to me, and will be the last to go. I found it easy, even to make the ice-cold fire and the wild fire, and the fire that goes like a whip through the dark; which is just as well, because I was young to be taught such things, and it is an art which, if you are unfit or unprepared, can strike you blind.
Author: Mary Stewart
From Goodreads: Born the bastard son of a Welsh princess, Myrddin Emrys—or as he would later be known, Merlin—leads a perilous childhood, haunted by portents and visions. But destiny has great plans for this no-man's-son, taking him from prophesying before the High King Vortigern to the crowning of Uther Pendragon . . . and the conception of Arthur -- king for once and always.
Little Notes: Stewart's tale of Wales-in-the-time-of-Merlin is vivid and sensory and three-dimensional, depicted in some of the better prose I've come across in epic fantasy—as I would have expected from the author of The Moon-Spinners. It's an Arthurian retelling, narrated by Merlin himself, but more fantastic than historical; it sources Geoffrey of Monmouth, who, the author admits, is a great storyteller and a lousy historian. On the other hand, it posits Merlin as more frequently a good scientist than a magician, so it's quite light on the supernatural for a fantasy novel.
My one criticism of any weight centers around Merlin's belief that all gods of light are one—which struck me as anachronistic, though I could be wrong. Christians like myself will probably find their suspension of disbelief challenged by the outworkings of that; for instance, when Merlin's One God directs him to aid in an adulterous seduction. That aside, however, I thought this novel was superb. I've picked up a number of Arthurian works, and this is the first I've managed to finish. It's beautifully done. I already have the sequel on order.
P.S. Christie, if you haven't read this book, you want to. :)