The low fire sputtered, its warmth contracting even further in the gloom of the sparsely furnished room. The friar working by a single candle at his high desk looked up in vexation at the sounds of unrestrained revelry floating across the river. He could do nothing – creation at the nib of the pen was won only as the mind soared free of the dross of worldly existence and the common folk could not be expected to realise that their merrymaking was clawing it back to earth.Roger Bacon’s writings had brought him respect and repute from across Christendom as well as criticism and dangerous enemies. His questing intellect had taken him down strange paths, leading him to the unshakeable belief that the mind of God could be revealed in His works of nature rather than the opinions of man. As a university schoolman he taught that the pursuit of philosophical knowledge was the high road to understanding; his sturdy principle, to accept only that which had been amply demonstrated before proceeding further.

A protracted burst of jollity cut through his thoughts again.

Outside a virginal carpet of snow lay over all, softening the outlines of town squalor. In charity he’d sent his serving boy away to join the merriment, but not before a stern homily on the temptations of the flesh. He was alone, in the upper floor of his eyrie with a dying fire for company.

Drawing his homespun robe closer Bacon got up to attend to the embers, so much poorer than the crackling splendour of the yule log on the opposite bank. The last mummers had finished their show and with Gog and Magog justly slain they were claiming their due in raucous style, careless shrieks of women mingling with jovial roars and laughter. He hesitated – was this not a thing of exemplary wonder, that as a portion of brightness and life against the blackness and unknowns of an evil world, it stood for God’s grace infilling the impure darkness of one’s soul? Perhaps.

He poked at the fire and was rewarded with a momentary blaze. He added a small log then went back to his desk.

But as he lifted his quill there was a sudden knocking at the door below.

There was no-one else now in this little building straddling the roadway over a bridge. Who could it be? He had no fear of robbers for the Franciscan mendicant order abjured wealth and display but his books and instruments were worth far more to him than tawdry adornments.

Should he answer the door? The sound had been too robust for a drunken well-wisher and seemed to indicate that this was a visitor who knew he was in.

He took the candle, descended the stairs and stood at the closed door.

‘Who is there?’ he called.

There was no reply. The peephole showed only a vague shape against the white luminosity of the snow.

He slid the bar up and the door creaked loudly as he opened it to reveal the figure of a large man in a cloak with a curiously pointed hood hiding his face.

‘What is your business, my son?’

‘Then you do not know me, holy brother.’

Bacon recognised the deep voice. ‘Why, by God’s sweet passion – it’s Brother William!’

The hood was flung back and there was his friend, the high-placed Flemish Franciscan, William of Rubruck.

‘Do I see you well, dear Roger?’

‘You do! Yes, upon my soul, and the better for seeing you! Do come in, this cold would perish even the warmest heart.’

He closed the door as Rubruck shook the snow off and declared mysteriously, ‘Which compared to where I’ve been fated to go is the merest breath of chill.’

‘Oh? Well, you shall tell me of it – but only after I offer you a fine posset.’ He found a pan in the deserted buttery along with milk, ale and nutmeg and they mounted the stairs to his study.

While Bacon busied himself heating the milk his visitor took off his cloak – dark and fur-lined, it was well-worn and oddly fashioned with its pointed hood all one with it.

‘It’s been too long, my sage and worthy friend. Let me see, the last time – was it not Paris and the ever-rational Peter Peregrinus, or was it–’

‘Dear brother, tonight I’ve come to you alone, to tell of my journeying.’

Something in his voice told Bacon that this was to be no mere recounting of a tale and his interest quickened. The travels of a wise man were always to be valued as a source of true knowledge of the world but he suspected there was more to it than that.

‘I’m to be honoured, William. Please go on.’

Rubruck stared at the fire for long moments before he began. ‘Know that His Grace King Louis of France has been much troubled by the grievous losses among the holy Crusaders at the hands of the Saracens and thought to take measures as would remedy this. In the year twenty-five of his reign he dispatched an envoy to the very court of the chief of the Mongols beseeching an alliance against the Mohammedan.’

‘Yes?’

‘Brother Roger, I was the one who led this mission.’

‘Ah. So you must travel into Asia, past Constantinople to the very lands of the Tartars.’

‘An immense journey, years in the making.’ With a distant look he went on, ‘To the capital of the Great Khan Mongke, which is Karakorum, on the far side of the world. Across a vastness unimaginable, a grass desert without end – all summer, a bitter winter and the great heat again for leagues beyond counting.’

‘Then you were granted sights of amazing wonder, which you know I’m with child to hear!’

‘In good time I shall write at length of these, but for now you must be content with-‘

‘The monsters who inhabit the boreal realm, the sciapods of one foot – the anthropophagi feasting on human flesh. I’ve given little credence to such tales but…?’

‘None did I see, neither they nor the kingdom of Prester John, my curious friend. Yet I stood at the mount of the Ark of Noah and the Iron Gate of Alexander the Macedonian, but never a great city, for they are a restless people and think not to plant a village, still less a town.’

‘May it be said that the Tartar in his home and hearth is nonetheless tutored, gentle in his manners?’

‘They ceaselessly travel in a horde, eat millet and meat all but raw for lack of fuel, consuming the fermented milk of mares, to which they add blood. They live in transportable houses of felt which they call “yurts” and their manners are…singular – they drink pot liquor and think nothing of doing their filthiness beside we talking together. And to revere their parents, they consume their dead flesh and drink from their very skull, in truth a benighted folk.’

‘I weep for your travails, dear William.’

‘Do not, I pray you brother, for is it not written in Ecclesiasticus, “He shall go through the land of foreign peoples, and shall try the good and evil in all things.” A deep saying and one I held close to my heart as I progressed through these odious lands.’

‘Then I must ask it – were you received at the court of the captain of the Tartars?’

‘Which is the Khagan Mongke, who was most obliging. Be aware, brother, that this is the chief of the peoples who have spread across the face of the earth like no other, whose word may set a host of ten thousand times ten thousand horsemen against any who challenge his will.’

Bacon blinked in wonder. ‘This capital will therefore be rich and splendid beyond all conceiving.’

‘Excepting stone turtles past counting and a wondrous tree crafted of lustrous silver I found it not much out of the ordinary.’

‘Yet you did enter in upon the palace of the chief of the Mongols.’

Rubruck paused a moment in reflection, then answered, ‘I did so, brother.’

‘And your mission – may it be said to have succeeded?’

‘I laid before him a letter from King Louis, translated by my man Homo Dei. His answer – that if such a one together with His Holiness the Pope should travel to do homage to himself, he promises good welcome. Naught else.’

‘There can be no reasoning with those who are blind to the wider world, I’m persuaded. Yet you will have a higher work – the bringing of the knowledge of Christ’s mercy to this horde!’

‘As you say. But they are a strange and perturbing race of men. They worship Tengri, the sky god and are never without their sorceries and idolatries. Superstition rules their lives – even the Great Khan does not eat until the soothsayers read the charred bones of sheep.’

‘No heathen is entirely lost to God’s grace.’

‘You will be astonished to learn that I discovered Christians already in attendance at his court.’

‘How can this be?’

‘They are none but Nestorians with their vile heresies. Together with a species of shameless idol-worshippers and a coven of sly Saracens. It passed that Khagan Mongke professed himself curious at the claims of the different faiths and set us all to debating their merits with each other together before him.’

‘Aha! A foolish pagan priest it is who wrangles with the Master of Rhetoric!’

‘Would that it were so. My interpreter was a contemptible creature who I doubt gave true meaning to my words, and besides which I was constrained to ally with the Nestorians against the infidels.’

He sighed. ‘The result you may conjecture when I tell you that on taking my leave I perceived my precious gold cross of St Francis, that I guarded so jealously over such vast a distance to present to him, was there on a wall – but side by side with every other abomination of heathen effigy.’

‘A dolorous conclusion to a journey of spirit and hardship,’ Bacon murmured in sympathy.

Rubruck looked up with a suddenly sombre expression. ‘As you must guess, my tale of far wandering is not the reason for my presence.’

‘You wish to discuss a great matter that troubles you.’

‘Just so, learned one.’

‘Then say on, dear brother.’

Rubruck rose and went to the window, opening the shutters and peering out cautiously.

‘There is no-one below us?’

‘None. The knaves have deserted me for their merry-making.’

‘That is good. For what I am about to divulge is for your ears alone, my good brother.’

‘Do sit and share with me your perplexity then, William,’ Bacon said.

‘It is no simple concern, you must believe. It touches on the future of Christendom itself.’

He paused as if collecting his thoughts. ‘In Karakorum oft-times the Great Khan was occupied by the affairs of state, leaving we envoys in idleness. You will know me as incurably desirous of knowledge, to promiscuously inquire and learn, and I could not abide that condition. Thus it was that I sought permission to make visit to the privy districts of his capital.’

‘You must have seen–’

‘It is one revelation alone that astonished and daunted me, my dear friend. One that shook my understanding of the workings of God in nature, the boundary of magic and sorcery – to feel the very trespass of the Devil on our world!’

Chilled by his words, Bacon tensed.

‘For what I am about to do, I ask forgiveness, for there is no other way to bring to you the sensations I felt as I first beheld this, that I now share with you.’

He rose and went to the window again, and satisfied of their privacy, closed the shutters. Feeling around in his leather pouch he drew out a small object which he inspected, then went to the candle and offered one end to the flame. It sputtered and fell to a red glow. He threw it to the floor and moved away quickly.

Astonished at his behaviour, Bacon could only watch from his chair.

A livid flash and clap of thunder stunned his senses and the room filled with acrid smoke and the fearful stink of brimstone.

Terrified, Bacon gripped his chair and stared into the gloom with a pounding heart, expecting to be confronted with the diabolical form of Beelzebub himself arising from the nether regions – but he saw only the silent figure of his friend through the slowly dissipating smoke.

‘Wh-what is it this you’re conjuring before me, Brother Rubruck?’ he croaked, crossing himself.

‘No deviltry, Roger, I swear to you.’ He bent to pick up some ashy fragments and placed them in Bacon’s uncomprehending hands.

‘The work of man.’

‘Then how…’

Rubruck turned over a plate on the serving table. ‘See here brother, the essence of the phenomenon.’

He brought out another pouch and carefully shook a small pile of grains as grey as his friar’s habit on the back of the plate, and leaned back to allow Bacon to see.

‘Now I bring fire.’

Bacon recoiled fearfully as a lighted taper touched one edge, but it only flared and spat merrily without violence.

‘Yet if I…’ Rubruck poured a similar sized amount but this time led a small trail out to one side. He placed a cup over the plate, brought the flame to it and stood back.

There was an instant’s fizz and a sharp pop. The cup flew into the air then fell to the ground to smash in pieces.

‘At the touch of fire the substance grows angry and if confined in its rage, it calls upon all the powers of a demon to free itself.’

‘This is marvellous in my sight,’ Bacon said shakily. ‘A deep mystery beyond imagining. Yet you say it’s the work of man…how is it that…?’

‘In his capital, the Great Khan maintains quarters for foreigners, artisans and craftsmen from far parts of his empire engaged in works to add splendour and lustre to his realm. Those of the Cathayans he particularly indulges, furnishing them with all they ask, for they are adepts in the greatest mystery of them all.’

‘This…this terrible dust.’

‘That they call huo yao. They make it from unspeakable ingredients by a long process that ends with what you see before you. Roger, hear me – I’ve seen them call forth torrid leaps of flame as from a dragon’s mouth, to send messengers on wings of fire to soar across the heavens and as you’ve seen, to bring thunder and lightning down to earth at their bidding, a hideous and miraculous sight.’

‘A terrible experience, William.’

‘Only as I felt it my duty to make investigation, as a scholar and philosopher must.’

‘Just so.’

‘And now to my dilemma, dear friend.’

‘I hear you with respect and admiration, brother.’

‘I thank you, and know also that you are the one out of all Christendom that I can think to bring my troubled mind.’

Bacon murmured a respectful acknowledgement.

‘So far as I can know it, the people of Cathay delight only in its ardent properties in spectacle and display, the capacity to affright and awe.’

‘This is understandable.’

‘Since that day I’ve struggled with my conscience before God. For want of curiosity in my companions, I, of all in my party, have been made witness to these terrors and portents. And only I, for whatever divine purpose, have been vouchsafed the secret of this infidel magic.’

Bacon caught his breath. ‘You learned of the spells to bring it into mortal existence?’

‘I questioned many artisans severally, all of whom gave the same answers. Yes, brother, I have the secret.’

‘Then…’

‘My dilemma is plain – do I reveal it or no? In the Europe of this dark century of war and hatred, when armies perpetually contend on the battlefield in slaughter and cruelty, how can I be sure that this dangerous knowledge will not be perverted to produce instruments of war more terrible by far than any seen to this day? There are many who would conceive it to be a mortal sin, I believe.’

Bacon leaned forward, intensity in his voice, ‘I, too, would so regard it so, brother. The secret must remain locked in your breast all your mortal days – it must never escape into this wicked world!’

‘As I at first concluded. Yet…yet as a philosopher and devoted to the arts of learning I’m sore distracted by the observation that should I be called to my rest this hour, there will be none in this kingdom to know of its existence, to perhaps pursue its properties unobserved and discover its vitality and significance. Brother Roger, I beg you will allow me to share this dread knowledge with you as a natural philosopher and relieve me of this heinous burden.’

Into the stillness came from the outside the same dull roar of revelry, but within the austere scholar’s study the fading reek of sulphur was a token of the frightful things that had passed.

‘Very well, Brother Rubruck, I shall accede to your request. But only on the condition that we do kneel and swear together the most sacred oath that this secret shall remain inviolate between us, never to be divulged to the profane and ignorant of this world.’

‘I am content at that.’.