The Colour of Magic by Terry Pratchett

opened the Book, which was chained to the octiron pedestal in the middle of the rune-strewn floor not lest someone steal it, but lest it escape; for it was the Octavo, so full of magic that it had its own vague sentience. One spell had indeed leapt from the crackling pages and lodged itself in the dark recesses of his brain. And, apart from knowing that it was one of the Eight Great Spells, no one would know which one until he said it. Even Rincewind did not. But he could feel it sometimes, sidling out of sight behind his Ego, biding its time…
    On the front of the Octavo had been a representation of Bel-Shamharoth. He was not Evil, for even Evil has a certain vitality—Bel-Shamharoth was the flip side of the coin of which Good and Evil are but one side.
    “The Soul Eater. His number lyeth between seven and nine; it is twice four,” Rincewind quoted, his mind frozen with fear. “ Oh no . Where’s the Temple?”
    “Hubward, toward the center of the forest,” said the dryad. “It is very old.”
    “But who would be so stupid as to worship Bel—him? I mean, devils yes , but he’s the Soul Eater—”
    “There were—certain advantages. And the race that used to live in these parts had strange notions.”
    “What happened to them, then?”
    “I did say they used to live in these parts.” The dryad stood up and stretched out her hand. “Come. I am Druellae. Come with me and watch your friend’s fate. It should be interesting.”
    “I’m not sure that—” began Rincewind.
    The dryad turned her green eyes on him.
    “Do you believe you have a choice?” she asked.

    A staircase broad as a major highway wound up through the tree, with vast rooms leading off at every landing. The sourceless yellow light was everywhere. There was also a sound like—Rincewind concentrated, trying to identify it—like far off thunder, or a distant waterfall.
    “It’s the tree,” said the dryad shortly.
    “What’s it doing?” said Rincewind.
    “Living.”
    “I wondered about that. I mean, are we really in a tree? Have I been reduced in size? From outside it looked narrow enough for me to put my arms around.”
    “It is.”
    “Um, but here I am inside it?”
    “You are.”
    “Um,” said Rincewind.
    Druellae laughed.
    “I can see into your mind, false wizard! Am I not a dryad? Do you not know that what you belittle by the name tree is but the mere four-dimensional analogue of a whole multidimensional universe which—no, I can see you do not. I should have realized that you weren’t a real wizard when I saw you didn’t have a staff.”
    “Lost it in a fire,” lied Rincewind automatically.
    “No hat with magic sigils embroidered on it.”
    “It blew off.”
    “No familiar.”
    “It died. Look, thanks for rescuing me, but if you don’t mind I think I ought to be going. If you could show me the way out—”
    Something in her expression made him turn around. There were three he-dryads behind him. They were as naked as the woman, and unarmed. That last fact was irrelevant, however. They didn’t look as though they would need weapons to fight Rincewind. They looked as though they could shoulder their way through solid rock and beat up a regiment of trolls into the bargain. The three handsome giants looked down at him with wooden menace. Their skins were the color of walnut husks, and under it muscles bulged like sacks of melons.
    He turned around again and grinned weakly at Druellae. Life was beginning to take on a familiar shape again.
    “I’m not rescued, am I?” he said. “I’m captured, right?”
    “Of course.”
    “And you’re not letting me go?” It was a statement.
    Druellae shook her head. “ You hurt the Tree . But you are lucky. Your friend is going to meet Bel-Shamharoth. You will only die.”
    From behind two hands gripped his shoulders in much the same way that an old tree root coils relentlessly around a pebble.
    “With a certain amount of ceremony, of course,” the dryad went on. “After