"Work your way through that lot," his master said dryly, "and you might be getting somewhere. That case contains the rites and incantations you'd need to summon significant demons; and you won't even begin to use them till you're in your teens, so cast it out of your mind. Your case"—he tapped the wood again—"gives you the preparatory knowledge and is more than enough for the moment. Right, follow me."

They proceeded to a workroom that Nathaniel had never visited before. A large number of bottles and vials clustered there on stained and dirty shelves, filled with liquids of varying color. Some of the bottles had floating objects in them. Nathaniel couldn't tell whether it was the thick, curved glass of the bottles that made the objects look so distorted and strange.

His master sat on a stool at a simple wooden worktable and indicated for Nathaniel to sit alongside him. He pushed a narrow box across the table. Nathaniel opened it. Inside was a small pair of spectacles. A distant memory made him shudder sharply.

"Well, take them out, boy; they won't bite you. Right. Now look at me. Look at my eyes; what do you see?"

Unwillingly, Nathaniel looked. He found it very difficult to peer into the fierce, fiery brown eyes of the old man, and as a result his brain froze. He saw nothing.

"Well?"

"Um, um… I'm sorry, I don't…"

"Look around my irises—see anything there?"

"Um…"

"Oh, you dolt!" His master gave a cry of frustration and pulled the skin below one eye down, revealing its red underbelly. "Can't you see it? A lens, boy! A contact lens! Around the middle of my eye! See it?"

Desperately, Nathaniel looked again, and this time he did see a faint circular rim, thin as a pencil line around the iris, sealing it in.

"Yes, sir," he said eagerly. "Yes, I see it."

"About time. Right." His master sat back on the stool. "When you are twelve years old, two important things will happen. First, you will be given a new name, which you shall take as your own. Why?"

"To prevent demons getting power over me by discovering my birth name, sir."

"Correct. Enemy magicians are equally perilous, of course. Secondly, you will get your first pair of lenses, which you can wear at all times. They will allow you to see through a little of the trickery of demons. Until that time you will use these glasses, but only when instructed to, and on no account are they to be removed from this workroom. Understand?"

"Yes, sir. How do they help see through things, sir?"

"When demons materialize, they can adopt all manner of false shapes, not just in this material realm, but on other planes of perception too—I shall teach you of these planes anon, do not question me on them now. Some demons of the higher sort can even become invisible; there is no end to the wickedness of their deceptions. The lenses, and to a lesser extent the glasses, allow you to look on several planes at once, giving you a chance of seeing through their illusions. Observe—"

Nathaniel's master reached over to a crowded shelf behind him and selected a large glass bottle that was sealed with cork and wax. It contained a greenish briny liquid and a dead rat, all brownish bristles and pale flesh. Nathaniel made a face. His master considered him.

"What would you say this was, boy?" he asked.

"A rat, sir."

"What kind?"

"A brown one. Rattus norvegicus, sir."

"Good. Latin tag too, eh? Very good. Completely wrong, but good nevertheless. It isn't a rat at all. Put on your glasses and look again."

Nathaniel did as he was told. The spectacles felt cold and heavy on his nose. He peered through the filmy pebble—glass, taking a moment or two to focus. When the bottle swam into view, he gasped. The rat was gone. In its place was a small black—and—red creature with a spongy face, beetle's wings, and a concertina—shaped underside. The creature's eyes were open and bore an aggrieved expression. Nathaniel took the spectacles off and looked again. The brown rat floated in the pickling fluid.

"Gosh," he said.

His master grunted. "A Scarlet Vexation, caught and bottled by the Medical Institute of Lincoln's Inn. A minor imp, but a notable spreader of pestilence. It can only create the illusion of the rat on the material plane. On the others, its true essence is revealed."

"Is it dead, sir?" Nathaniel asked.

"Hmm? Dead? I should think so. If not, it'll certainly be angry. It's been in that jar for at least fifty years—I inherited it from my old master."

He returned the bottle to the shelf. "You see, boy," he went on, "even the least powerful demons are vicious, dangerous, and evasive. One cannot withdraw one's guard for a moment. Observe this."

From behind a bunsen burner, he drew a rectangular glass box that seemed to have no lid. Six minute creatures buzzed within it, ceaselessly butting against the walls of their prison. From a distance they seemed like insects; as he drew closer, Nathaniel observed that they had rather too many legs for this to be so.

"These mites," his master said, "are possibly the lowest form of demon. Scarcely any intelligence to speak of. You do not require your spectacles to see their true form. Yet even these are a menace unless properly controlled. Notice those orange stings beneath their tails? They create exquisitely painful swellings on the victim's body; far worse than bees or hornets. An admirable method of chastising someone, be it annoying rival… or disobedient pupil."

Nathaniel watched the furious little mites butting their heads against the glass. He nodded vigorously. "Yes, sir."

"Vicious little things." His master pushed the box away. "Yet all they need are the proper words of command and they will obey any instruction. They thus demonstrate, on the smallest scale, the principles of our craft. We have dangerous tools that we must control. We shall now begin learning how to protect ourselves."

Nathaniel soon found that it would be a long time before he was allowed to wield the tools himself. He had lessons with his master in the workroom twice a week, and for months he did nothing except take notes. He was taught the principles of pentacles and the art of runes. He learned the appropriate rites of purification that magicians had to observe before summoning could take place. He was set to work with mortar and pestle to pound out mixtures of incense that would encourage demons or keep unwanted ones away. He cut candles into varying sizes and arranged them in a host of different patterns. And not once did his master summon anything.

Impatient for progress, in his spare time Nathaniel devoured the books in the library case. He impressed Mr. Purcell with his omnivorous appetite for knowledge. He worked with great vigor in Ms. Lutyens's drawing lessons, applying his skill to the pentacles he now traced under the beady eye of his master. And all this time, the spectacles gathered dust on the workroom shelf.

Ms. Lutyens was the only person to whom he confided his frustrations.

"Patience," she told him. "Patience is the prime virtue. If you hurry, you will fail. And failure is painful. You must always relax and concentrate on the task in hand. Now, if you're ready I want you to sketch that again, but this time with a blindfold."

Six months into his training, Nathaniel observed a summoning for the first time. To his deep annoyance, he took no active part. His master drew the pentacles, including a secondary one for Nathaniel to stand in. Nathaniel was not even allowed to light the candles and, what was worse, he was told to leave the spectacles behind.

"How will I see anything?" he asked, rather more pettishly than was his habit with his master; a narrow—eyed stare instantly reduced him to silence.

The summoning began as a deep disappointment. After the incantations, which Nathaniel was pleased to find he largely understood, nothing seemed to happen. A slight breeze blew through the workroom; otherwise all was still. The empty pentacle stayed empty. His master stood close by, eyes shut, seemingly asleep. Nathaniel grew very bored. His legs began to ache. Evidently this particular demon had decided not to come. All at once, he noticed with horror that several of the candles in one corner of the workroom had toppled over. A pile of papers was alight, and the fire was spreading. Nathaniel gave a cry of alarm and stepped—