‘The place I want you to visit,’ said Linius Pallitax, ‘is the Great Library.’

  Quint's brow furrowed. ‘The Great …’ He paused. ‘I don't think I know where that is.’

  ‘Very few academics do, I'm afraid. It was an ancient centre for earth-studies. These days it is most unfashionable. Nobody goes there any more,’ said the professor, and tutted unhappily. ‘Sky above, have we really come so far?’ he murmured. ‘Here I am, Most High Academe of a place where the very presence of the Great Library is ignored.’

  The High Academe's eyes had a faraway look in them. He seemed to be talking to himself. ‘Oh, it was a sad day indeed when the schism between earth-studies and sky-scholarship first occurred.’ He glanced round nervously, as if worried that someone might be listening. ‘Don't misunderstand me, lad. I am not saying that sky-scholarship is not invaluable. After all, were it not for the windtouchers and raintasters and, yes, the mistsifters also, we wouldn't know about stormphrax. And without stormphrax to weight down the floating rock, then Sanctaphrax itself would break its moorings and then everything would be lost. And yet…’ his eyes misted over, ‘the old scholars of earth-studies had accumulated so much knowledge…’

  Quint listened closely, trying to take it all in.

  ‘About the properties of plants, the qualities of minerals, the secrets of trees. And living creatures! They listed and sorted and classified and categorized the Deepwoods more precisely than even the Professors of Light and Darkness grade luminosity. And that's saying something, I can tell you!’

  Quint looked suitably impressed.

  ‘The problem, my lad, is that the knowledge they accumulated over the centuries is being lost. Despite my best efforts to revive it, earth-studies is ignored and the place where its wealth of information is stored – the Great Library – has been abandoned and left to fall into utter neglect. Even as we speak, the priceless barkscrolls and tomes it houses are crumbling to dust.’ He sighed.

  ‘And it is knowledge we cannot afford to lose…’

  ‘Can't we go and tidy the place up a bit?’ Quint suggested. ‘Sort things out?’

  ‘Oh, Quint,’ said Linius wearily. ‘You haven't a clue what you're saying. A hundred academics could work there for a thousand days and still barely scratch the surface.’

  ‘Then what do you want me to do?’ said Quint.

  Outside, the departing white ravens flashed past the windows. Agitated, the professor began plucking at his fingers again, one after the other. ‘I want you to fetch me a barkscroll,’ he said.

  ‘Is that all?’ said Quint, smiling.

  The colour drained from the professor's face. ‘This is no laughing matter, lad,’ he said coldly. ‘I would go myself, but my leg is still not up to it.’

  ‘I'm sorry,’ said Quint. ‘I didn't mean…’

  ‘I cannot impress upon you enough the importance of your task,’ the professor continued. ‘If you fail, then…’ A shudder ran the length of his body. ‘You must not fail.’

  Quint nodded solemnly. Linius looked up to see the flock of white ravens, still streaming past his windows.

  ‘Listen well,’ he said. ‘Tweezel will give you precise directions to the Great Library. Once inside, the layout is complicated to the uninitiated, but not impossible to negotiate. It is set out like a forest – filled with trees of knowledge, so to speak. Each tree has a core subject –Aquatic Vegetation, Earth Organisms, that sort of thing. You'll find the exact academic discipline on a small plaque nailed to the trunk. The core subject you are looking for is Aerial Creatures.’

  ‘Aerial Creatures,’ Quint repeated, committing it to memory.

  ‘You are to climb into that tree,’ said Linius. ‘The higher you climb, the more branches you will come to. By following the words and symbols carved into the bark, you must climb up the relevant branches – each one representing a branch of the subject – until you home in on the barkscroll I need.’

  ‘It sounds complicated,’ said Quint.

  ‘That is why you must listen carefully,’ said Linius. As he spoke, the stragglers of the huge flock flapped past the windows and a plaintive cawing began. ‘Oh, no,’ he whispered nervously, ‘I shall be late again.’

  ‘Late for what?’ asked Quint.

  ‘As Most High Academe, it is my duty to bless the ritually purified academics who are about to harvest the flight-rocks,’ he said. ‘They may not go to the Stone Gardens until I have.’ He wiped his sweating brow on his sleeve. ‘So much to do and so little time,’ he muttered and, once again, Quint couldn't help but notice how exhausted the Most High Academe looked.

  ‘Then tell me exactly how to find this barkscroll,’ said Quint. ‘And quickly.’

  ‘You must take what is known as the negative ascent,’ the professor explained. ‘At the first fork you will come to bird and not bird. Take not bird. At the second fork,reptile and not reptile. Take not reptile. At the third fork,mammal and not mammal.’

  ‘And I take not mammal,’ said Quint.

  ‘Precisely,’ said Linius. ‘Do this so long as the option allows. Then it becomes more tricky – and the branches rather slender – so do use the walkways and hanging-baskets provided. You need to find two twigs, one marked legendary …’

  ‘Legendary,’ said Quint.

  ‘The other marked celestial.’

  Quint nodded.

  ‘Hanging from the point where these two cross, you will find the barkscroll I need.’ He breathed out noisily. ‘Now have you got all that?’

  ‘I think so,’ Quint said. ‘Aerial Creatures. Not, not, not, as far as I can go. Then legendary and celestial.’

  ‘Well done,’ said Linius. ‘You make it sound easy. I only hope you don't find it too difficult in reality.’

  ‘You can count on me,’ said Quint confidently.

  ‘I hope so,’ said the professor darkly. ‘As I said before, Quint, you must not fail. So, keep your mind on the task at hand at all times and do not let yourself be distracted.’

  He turned and picked up his stave.

  ‘Now, go, lad. And Sky speed be with you.’ He sighed. ‘I must go and see to my blessed academics.’

  Head spinning with Tweezel's directions and the professor's instructions, Quint stepped outside the Palace of Shadows. It came, as it always did, as quite a shock to Quint when he stepped outside to find that it was still the middle of the afternoon – and sunny. Since the Palace of Shadows was completely surrounded by tall buildings which kept it in the shade, daylight was a constant twilight and even the sunniest day seemed overcast. As he emerged from the narrow alley onto the broad central concourse opposite the Central Viaduct, he had to raise his hand to shield his eyes from the dazzling sun.

  ‘Which way?’ he muttered, and answered himself in the same breath with Tweezel's words, ‘At the southern end of the Viaduct Steps.’

  A week earlier even this would have confused him, and he remembered how Maris had laughed at him when he'd headed in completely the wrong direction to the West Landing. The thing was, the compass directions of Sanctaphrax had been fixed before the floating rock had become buoyant. Now that the great rock was floating in mid-air and turning constantly, the so-called southern end could have been anywhere – except that Quint had recently learnt that the towering Loftus Observatory was at the southern end of the Central Viaduct, and it was that way he headed, skirting along its West Steps.

  In the week he'd been in Sanctaphrax, Quint had learned a lot about the great floating city. His school day started at the unearthly hour of six in the morning,but finished at one, which meant that his afternoons were free. Every one, he had spent walking around, getting to know the various schools, colleges and faculties, familiarizing himself with its avenues and walkways; its bridges and landing-stages, large and small. The Viaduct Steps, in particular, fascinated him.

  High above, the Central Viaduct itself was a magnificent structure, forming the main thoroughfare between the Loftus Observatory and the Great Hall. Line
d by some two hundred small towers of the lesser academic faculties – anything from bark-reading to moon-chanting – it stood astride twenty-four mighty pillars. Beneath and between these were the Viaduct Steps, east and west sloping.

  At first, Quint had paid little attention to the shifting groups of clustered academics on the marble steps. But as the days passed, he started to notice the same characters in the same places doing the same things, and began eavesdropping on their conversations.

  The twelfth West Steps, for instance, was the place where young apprentices would furtively swap exam papers and gossip about their professors. The eighteenth, in contrast, was a place where academics with a grievance would air them publicly, and often to a huge audience. While on the other side, the eighteenth East Steps hosted fromp-fighting and illicit gambling…

  On this particular afternoon, however, with the urgency of the Most High Academe's instructions still ringing in his ears, Quint did not dawdle – tempted though he was. He hurried on past staircase after staircase of feverish activity without once pausing, round the base of the Loftus Observatory, and stopped in his tracks. His jaw dropped.

  How in Sky's name did I miss that? he wondered, staring at the vast wooden structure before him. He noted the simple design: a low circular wall surmounted by a tall fluted roof like a giant umbrella, all topped off with a modest observation tower. Unlike its tall, showy neighbours – which, in every way, put the ancient library into the shade – it simply did not stand out.

  Quint crossed the shadow-filled square and disappeared into the still deeper shade beneath the great roof. No-one noticed him walk round the curving wall or stumble across the concealed door. And no-one saw him enter.

  ‘Wow!’ he gasped. If the outside of the Great Library had surprised Quint, then the inside left him utterly breathless. It was vast, yet deserted. It was cool and silent. It smelled faintly of pine-sap with an ominous hint of leaf-mould. It was like nothing he had ever experienced before.

  The ‘trees’ that Linius had described were massive vertical columns of wood set into the packed-earth floor, with pegs up their sides to serve as hand- and footholds; the ‘branches’ were an intricate system of arches and cross-beams far, far up above his head. There were platforms and decking attached to the trunks at various heights, and ladder-ways and pulley-ropes with

  hanging-baskets connecting one tree to another. And suspended on wires from the ‘twigs’ were the bark-scrolls themselves. Some hung individually, like leaves. Others hung in bunches, fifty or so at a time, in large holders. Some, having fallen away completely, had turned the floor into a scene reminiscent of the Deepwoods in autumn.

  Quint crouched down, retrieved a scrap of barkscroll and unrolled it carefully on the ground. As he did so, he thought he saw several shining things – objects or creatures, it was not clear – gliding across the floor. But when he looked round, there was nothing to be seen.

  Returning his attention to the barkscroll, he smoothed his hand over its leathery parchment surface and looked at it closely. The text – all neatly written in a minute, feathery script, and accompanied by annotated sketches and charts – concerned banderbears, or rather the pale sytil moss which grew in their thick fur and gave the huge lumbering Deepwoods-dwelling creatures their green hue. The detail was phenomenal.

  ‘And this is just a scrap from one single barkscroll,’ Quint muttered, amazed. ‘One of countless thousands,’ he added, looking up at the hanging holders. ‘The sheer amount of knowledge! What an incredible place this Great Library is.’ He climbed to his feet. ‘But don't let yourself become distracted,’ he reminded himself sharply. ‘Just find the barkscroll the professor wants and get it back to him as soon as possible.’

  This, he soon discovered, was much easier said than done. Not only were there more than a hundred of the tree-pillars to check through, but the plaques which differentiated them were written in a curling script which Quint found almost impossible to decipher.

  ‘S-o-c-i-a-l-G-e-s-t – Social Gestures,’ he said, tracing his fingers over the unfamiliar letters. He moved on to the next. G— No, C-a-r-n … Carnivorous F … Flora. And the next. And the next. Gradually the letters became easier to read. The As were like Ss, the Fs were like Ts, the Cs were like Gs. He moved more and more quickly from tree-pillar to tree-pillar, searching systematically for the one core subject he had to find.

  But as the time passed – half an hour, an hour, two hours – Quint became more worried and his searching increasingly frenzied. What if he'd somehow missed the one he was looking for? What if he couldn't find it before sundown? – there didn't seem to be any working lights in the library.

  The professor's doom-laden words echoed round his head – You must not fail! – over and over, like the tolling of a bell. But what if he did fail?

  ‘Pull yourself together,’ he told himself. ‘It is here. And I shall find it.’ There were still ten tree-pillars to go. Quint ran from one to the other reading off the plaques but, as he feared, not one of them bore the name Aerial Creatures. If his calculations were correct, then he was right back where he'd started from.

  He crouched down by the one in front of him. ‘Yes, that was the one,’ he muttered to himself. ‘Social Gestures… Except. Hang on a moment.’ He leaned forwards for a closer look. ‘I don't believe it!’ he exclaimed. ‘This is the one! Aerial Creatures. I can see it now. And to think that it was the very first one I looked at!’

  Furious with himself for his mistake, yet relieved beyond words to have finally found the right tree-pillar, Quint wasted no time in scampering up the pegs. He was agile, with nimble fingers and an excellent head for heights. His burnt hand had healed well enough for him to climb with no discomfort and, having lived on a sky pirate ship for years – forever shinning up masts and negotiating sky-rigging – the ascent offered no difficulty. He was soon at the first fork.

  ‘Bird. Not bird,’ he read, the words carved into the wood in the same floral script.

  As instructed, he chose not bird and continued. From this point on, although the climb was no longer vertical, because the pegs had stopped he needed to take great care not to slip and fall – especially since the light was beginning to fail.

  Further up the professor's so-called ‘negative ascent', the choices began to get weirder. At first, Quint gave it little thought, simply taking the not option each time, but it wasn't long before he was questioning exactly what sort of aerial creature the barkscroll dealt with. Inevitable/not inevitable. Stable/not stable. Sane/not sane.

  ‘Unstable and insane,’ Quint muttered uneasily, and he found himself wondering why the professor would want information on such an unpleasant-sounding creature. Did he have one? Did he want one? What type of a person was the professor anyway? And more important than any of these questions, where was the next something/not something to choose from?

  Having fumbled about in the near darkness of the vaulting for the previous ten minutes without finding any trace of lettering carved into the bark, Quint was feeling worried. He was on a thin, almost horizontal branch, far, far above the library floor. Despite his natural agility, the situation was not good. Every time he moved, the branch swayed ominously. If it should break, he would tumble into the darkness to certain death below. He tried hard to remain calm.

  ‘You must have reached the end of the negative ascent,’ he told himself. He looked round awkwardly. In the darkness, he could just make out the shapes of various barkscrolls hanging around him. Some were on their own, some in the holders. As for finding which specific one the professor wanted… ‘Find two twigs,’ he had said. What were they again? Legendary and … and … and what? His head spun. His legs shook. He hadn't come so far to fail now – yet, try as he might, he could not remember…

  ‘Blast,’ he muttered and, though softly spoken, the word echoed round and round the circular building, desecrating the hushed stillness of the library before fading away. At the same time, the full moon appeared from behind the clouds and s
hone down through the windows of the crown-like tower above Quint's head. Light – wonderful silver light – flooded into the Great Library.

  ‘Celestial,’ said Quint happily. ‘That was it. I …’ As the narrow branch bucked and dived, he groaned queasily and clung on ferociously, his cheek pressed to the wood. Gradually, the swaying steadied. Quint looked round. Then up. Then down. ‘Thank Sky for that,’ he whispered.

  In the silvery moonlight, Quint had seen that there was no longer any need for him to remain on the ‘tree’ at all. He was now up in the well-ventilated, pest-free environment – the air heady with the scent of pine-sap – where the barkscrolls hung. Here, where the librarians of old would have worked, were the ladder-ways and hanging-baskets on rope-pulleys which connected the trees, and gave access to the scrolls that he had seen from below.

  With a sigh of relief, Quint edged back a little and lowered himself down into the nearest basket. A cloud of dust sparkled in the moonlight as it sprinkled down from the rope it was suspended from.

  By tugging on the pulley-rope, Quint pulled himself further along, checking every twig-like protuberance he passed, as well as the occasional barkscroll. The fact was, the further he went and the more he saw, the greater his curiosity was becoming about these earth-studies academics who had devised such an intricate system of categorization and been fit and agile enough to use it. The search continued until, with a whoop of delight, Quint announced to the echoing air that he had found what he was looking for.

  ‘Legendary,’ he read off, ‘and celestial.’ He looked up and saw – just as the professor had said – that where the two of them crossed, a single barkscroll was hanging. Quint grinned. ‘There you are!’

  All those hours of searching, and finally he'd found what he was looking for. He tugged at the pulley-rope to manoeuvre himself forwards. The basket lurched, but stayed where it was. Quint pulled on the rope again, harder this time and, when that did nothing, once again. Still nothing.