'Because the Corpus hermeticum was used by heretics like Bruno and Campanella to justify their attacks on Rome.'

'And dozens more besides them. Yes. But with one stroke Professor Casaubon did away with a thousand years of magic, superstition and, in the eyes of Rome, heresy. After the texts had been dated, a new one was valueless, hardly of interest to anyone except a few half-mad astrologers and alchemists. It therefore made the perfect disguise.'

'Disguise?' I shifted uneasily on my chair, still struggling to understand. 'What do you mean?'

'Have you not guessed, Mr. Inchbold?'

She laid the thin volume aside, and before the wind riffled the pages I saw that the top half of the front one was now covered in the blue script, the ghost of a former text summoned back to life by her poisonous concoction. She dabbed carefully at the ink with a piece of blotting paper and then closed the cover. The wind had begun whistling in the necks of the flasks, raising an eerie chorus. A piece of dislodged slate clattered against the gutter and fell to the ground. The casement slammed shut. Alethea pushed back her chair and rose from the work-table.

'The Labyrinth of the World was only the reinscription,' she said at last, 'only the surface text. It was a forgery like the others, an invention used by Sir Ambrose to occult another text, one that was much more valuable. One in which the cardinals in the Holy Office would have interested themselves.' Carefully she stoppered the vial of cyanide. 'Many others as well.'

'Which text? Another heresy?'

'Yes. A new one. For if one world died in 1614, another was being born. In the same year that Casaubon published his attack on the Corpus hermeticum, Galileo printed three letters in defence of his Istoria e dimostrazioni, which had been published a year earlier in Rome.'

'His work on sunspots,' I nodded, perplexed. 'The work in which for the first time he defends Copernicus's model of the universe. Though I fail to see what-'

'By 1614,' she continued, oblivious, 'Ptolemy had been vanquished along with Hermes Trismegistus, his fellow Egyptian. Together the two of them were responsible for more than a thousand years of error and delusion. But the cardinals and consultors in Rome were less willing to accept the downfall of the astronomer than the shaman, and so the letters that Galileo published in 1614 are a plea for them to read the Bible for moral instead of astronomical lessons, to continue their practice of reading the Holy Scripture allegorically wherever it conflicts with scientific discoveries. All in vain, of course, since in the next year one of the letters was laid before the Inquisition.'

'So the text is one published by Galileo?' I was remembering Salusbury's translation of the Dialogo, the volume responsible for the astronomer's persecution by the Pope, the one whose contents Galileo had been forced to recant. 'One suppressed by Rome after the Holy Office banned Copernicanism in 1616?'

She shook her head. She was standing before the window with her hand resting lightly on the telescope, which she had carefully replaced on its tripod. Through the fogged panes I could see that the coach toiling through the mud had drawn a little closer. Nearer to the house I could make out through the curtains of rain the whorled outlines of the hedge-maze; even from this height, it looked hopelessly confused, an endless warren of curlicues and cul-de-sacs.

'No,' she replied, taking a small bucket from the work-table and picking her way into the corridor. 'This particular document was never published.'

'Oh? What is it, then?'

Water was not so much dripping as streaming through the ceiling. I watched as she stooped and placed the bucket beneath, in the middle of the puddle, then straightened.

'The parchment will keep for now,' she said. 'Let us continue our talk elsewhere.'

I took a last look through the window-the coach had disappeared behind a stand of trees-and followed her to the top of the staircase. Who was inside the vehicle? Sir Richard Overstreet? All at once I felt even more uneasy.

I gripped the banister and began to descend. I was about to say something, but after only two steps she stopped and turned round so quickly that I almost bumped into her.

'I wonder,' she said, looking at me with a kind of avid amusement, 'how much you know about the legend of El Dorado.'

Chapter Eight

The smell of the library was in sharp contrast to that of the laboratory. Everything about the cavernous chamber was precisely as I remembered, only now the pleasantly musty air was spiced with the familiar aromas of cedarwood oil and lanolin, as well as a resinous tang of new wood, for a few of the shelves had been repaired and the railing in the gallery replaced. The scents reminded me of my own shop, for smells always return us to the past more keenly and swiftly than any other stimulation. All at once I felt the same gust of heartsickness as on that last morning in the Half Moon Tavern. It might have been years rather than days since I last saw my home.

Alethea was motioning for me to take one of the leather-upholstered chairs beside the window. These too were new, as was the walnut table separating them and the hand-knotted rug, complete with monkeys and peacocks, on which they sat. I shuffled across the floor and obediently creaked into one of the chairs. Phineas was nowhere to be seen. Even his trail of blood had disappeared. For a second I entertained the notion that the disgraceful altercation had been only a product of my feverish imagination.

I crossed and uncrossed my legs, waiting for Alethea to speak. In those days I knew a little about the myth of El Dorado, or 'the Golden One', that will-o'-the-wisp that for the best part of a century had lured countless adventurers into the dangerous labyrinth of the Orinoco river. It is mentioned by chroniclers of the Spanish conquests such as Fernándo de Oviedo, Cieza de León and Juan de Castellanos, all of whose works I had briefly consulted in those first few days after my return from Pontifex Hall, and all of whom tell conflicting versions of the story. Rumours of El Dorado had reached the ears of the conquistadores soon after Francisco Pizarro's conquest of Peru in 1530: a city of gold governed by a valiant one-eyed chieftain, el indio dorado, whose practice it was to paint his body each morning in the dust of gold fished from the Orinoco, or perhaps from the Amazon… or perhaps from one of their hundreds of tributaries snaking through the jungles. The Spaniards were intrigued by the rumours, and in 1531 a captain named Diego de Ordás received a capitulación from the Emperor Charles V to ascend the Orinoco in search of this new Montezuma and his city of gold. Although he found no sign of it, other would-be discoverers were undaunted, and for the next few decades one conquistador after another set off into the jungle like knights-errant in the romances of chivalry so popular at the time. One of them, a man named Jiménez de Quesada, tortured any Indians he found by burning the soles of their feet and dropping bacon fat on their bellies. Under these encouragements his victims told stories of a hidden city of gold-now sometimes called either 'Omagua' or 'Manoa'-in the middle of the Guianan jungle, or perhaps even, like Tenochtitlán, in the middle of a lake.

But Quesada found nothing, nor did his niece's husband, Antonio de Berrío, a veteran explorer of the Orinoco and its tributaries whom Sir Walter Raleigh captured after the sack of Trinidad in 1595. That same year the Englishman, fired by the legends, ascended the Orinoco with a hundred men and provisions for a month. Only when the supplies were exhausted did he return to England, taking with him the son of an Indian chieftain and leaving behind to explore the river two of his most trusted crewmen. One of them was captured by Spanish soldiers, though not before he sent back to England a crude map showing the supposed site of a gold mine at the confluence of the Orinoco and Caroní rivers. But it would be another twenty years before Raleigh returned to Guiana for his disastrous final voyage, this time in the company of Sir Ambrose Plessington.