Butterfly Effect ; H. Potter

115. into the cave.

Dumbledore was standing in the middle of the cave, his wand held high as he turned slowly on the spot, examining the walls and ceiling.

"Yes, this is the place," said Dumbledore.

"How can you tell?" Harry spoke in a whisper.

"It has known magic," said Dumbledore simply.

Harry could not tell whether the shivers he was experiencing were due to his spine-deep coldness or to the same awareness of enchantments. He watched as Dumbledore continued to revolve on the spot, evidently concentrating on things Harry could not see.

"This is merely the ante-chamber, the entrance hall," said Dumbledore after a moment or two. "We need to penetrate the inner place ... now it is Lord Voldemort's obstacles that stand in our way, rather than those nature made ..."

Dumbledore approached the wall of the cave and caressed it with his blackened fingertips, murmuring words in a strange tongue that Harry did not understand. Twice Dumbledore walked right around the cave, touching as much of the rough rock as he could, occasionally pausing, running his fingers backwards and forwards over a particular spot, until finally he stopped, his hand pressed flat against the wall.

"Here," he said. "We go on through here. The entrance is concealed."

Harry did not ask how Dumbledore knew. He had never seen a wizard work things out like this, simply by looking and touching; but Harry had long since learned that bangs and smoke were more often the marks of ineptitude than expertise.

Dumbledore stepped back from the cave wall and pointed his wand at the rock. For a moment, an arched outline appeared there, blazing white as though there was a powerful light behind the crack.

"You've d-done it!" said Harry through chattering teeth, but before the words had left his lips the outline had gone, leaving the rock as bare and solid as ever. Dumbledore looked round.

"Harry, I'm so sorry, I forgot," he said; he pointed his wand at Harry, and at once Harry's clothes were as warm and dry as if they had been hanging in front of a blazing fire.

"Thank you," said Harry gratefully, but Dumbledore had already turned his attention back to the solid cave wall. He did not try any more magic, but simply stood there staring at it intently, as though something extremely interesting was written on it. Harry stayed quite still; he did not want to break Dumbledore's concentration.

Then, after two solid minutes, Dumbledore said quietly, "Oh, surely not. So crude."

"What is it, Professor?"

"I rather think," said Dumbledore, putting his uninjured hand inside his robes and drawing out a short silver knife of the kind Harry used to chop potion ingredients, "that we are required to make payment to pass."

"Payment?" said Harry. "You've got to give the door something?"

"Yes," said Dumbledore. "Blood, if I am not much mistaken."

"Blood?"

"I said it was crude," said Dumbledore, who sounded disdainful, even disappointed, as though Voldemort had fallen short of the standards Dumbledore expected. "The idea, as I am sure you will have gathered, is that your enemy must weaken him or herself to enter. Once again, Lord Voldemort fails to grasp that there are much more terrible things than physical injury."

"Yeah, but still, if you can avoid it ..." said Harry, who had experienced enough pain not to be keen for more.

"Sometimes, however, it is unavoidable," said Dumbledore, shaking back the sleeve of his robes and exposing the forearm of his injured hand.