“Fantastic!” William said. “More and more interesting!” He looked around. “But it would be better not to expose this discovery to the tricks of our mysterious companion, if he is still here…” He took off his lenses, set them on the desk, then carefully rolled up the parchment and hid it inside his habit. Still amazed by this sequence of events, which were nothing if not miraculous, I was about to ask further explanations when all of a sudden a sharp sound distracted us. It came from the foot of the east stairway, leading to the library.
“Our man is there! After him!” William shouted, and we flung ourselves in that direction, he moving faster, I more slowly, for I was carrying the lamp. I heard the clatter of someone stumbling and falling. I ran, and found William at the foot of the steps, observing a heavy volume, its binding reinforced with metal studs. At that same moment we heard another noise, in the direction from which we had come. “Fool that I am!” William cried. “Hurry! To Venantius’s desk!”
I understood: somebody, from the shadows behind us, had thrown the volume to send us far away.
Once again William was faster than I and reached the desk first. Following him, I glimpsed among the columns a fleeing shadow, taking the stairway of the west tower.
Seized with warlike ardor, I thrust the lamp into William’s hand and dashed blindly off toward the stairs where the fugitive had descended. At that moment I felt like a soldier of Christ fighting all the legions of hell, and I burned with the desire to lay my hands on the stranger, to turn him over to my master. I tumbled down almost the whole stairway, tripping over the hem of my habit (that was the only moment of my life, I swear, when I regretted having entered a monastic order!); but at that same instant — and it was the thought of an instant — I consoled myself with the idea that my adversary was suffering the same impediment. And, further, if he had taken the book, he would have his hands full. From behind the bread oven I almost dived into the kitchen, and in the starry light that faintly illuminated the vast entrance, I saw the shadow I was pursuing as it slipped past the refectory door, then pulled this shut. I rushed toward the door, I labored a few seconds opening it, entered, looked around, and saw no one. The outside door was still barred. I turned. Shadows and silence. I noticed a glow advancing from the kitchen and I flattened myself against a wall. On the threshold of the passage between the two rooms a figure appeared, illuminated by a lamp. I cried out. It was William.
“Nobody around? I foresaw that. He didn’t go out through a door? He didn’t take the passage through the ossarium?”
“No, he went out through here, but I don’t know where!”
“I told you: there are other passages, and it’s useless for us to look for them. Perhaps our man is emerging at some distant spot. And with him my lenses.”
“Your lenses?”
“Yes. Our friend could not take the page away from me, but with great presence of mind, as he rushed past, he snatched my glasses from the desk.”
“Why?”
“Because he is no fool. He heard me speak of these notes, he realized they were important, he assumed that without my lenses I would be unable to decipher them, and he knows for sure that I would not entrust them to anyone else. In fact, now it’s as if I didn’t have them.”
“But how did he know about your lenses?”
“Come, come. Apart from the fact that we spoke about them yesterday with the master glazier, this morning in the scriptorium I put them on to search among Venantius’s papers. So there are many people who could know how valuable those objects are to me. Actually, I could read a normal manuscript, but not this one.” And he was again unrolling the mysterious parchment. “The part in Greek is written too fine and the upper part is too hazy…”
He showed me the mysterious signs that had appeared as if by magic in the heat of the flame. “Venantius wanted to conceal an important secret, and he used one of those inks that leave no trace when written but reappear when warmed. Or else he used lemon juice. But since I don’t know what substance he used and the signs could disappear again: quickly, you who have good eyes, copy them at once as faithfully as you can, perhaps enlarging them a bit.” And so I did, without knowing what I was copying. It was a series of four or five lines, really necromantic, and I will reproduce only the very first signs, to give the reader an idea of the puzzle I had before my eyes:
When I had finished copying, William looked, unfortunately without lenses, holding my tablet at some distance from his nose. “It is unquestionably a secret alphabet that will have to be deciphered,” he said. “The signs are badly drawn, and perhaps you copied them worse, but it is certainly a zodiacal alphabet. You see? In the first line we have” — he held the page away from him again and narrowed his eyes with an effort of concentration — “Sagittarius, Sun, Mercury, Scorpio…”
“And what do they mean?”
“If Venantius had been ingenuous he would have used the most common zodiacal alphabet: A equals Sun, B equals Jupiter… The first line would then read … Try transcribing this:RACQASVL …” He broke off. “No, it means nothing, and Venantius was not ingenuous. He reformulated the alphabet according to another key. I shall have to discover it.”
“Is it possible?” I asked, awed.
“Yes, if you know a bit of the learning of the Arabs. The best treatises on cryptography are the work of infidel scholars, and at Oxford I was able to have some read to me. Bacon was right in saying that the conquest of learning is achieved through the knowledge of languages. Abu Bakr Ahmad ben Ali ben Washiyya an-Nabati wrote centuries ago a Book of the Frenzied Desire of the Devout to Learn the Riddles of Ancient Writings, and he expounded many rules for composing and deciphering mysterious alphabets, useful for magic practices but also for the correspondence between armies, or between a king and his envoys. I have seen other Arab books that list a series of quite ingenious devices. For example, you can substitute one letter for another, you can write a word backward, you can put the letters to reverse order, using only every other one; and then starting over again, you can, as in this case, replace letters with zodiacal signs, but attributing to the hidden letters their numerical value, and then, according to another alphabet, convert the numbers into other letters…”
“And which of these systems can Venantius have used?”
“We would have to test them all, and others besides. But the first rule in deciphering a message is to guess what it means.”
“But then it’s unnecessary to decipher it!” I laughed.
“Not exactly. Some hypotheses can be formed on the possible first words of the message, and then you see whether the rule you infer from them can apply to the rest of the text. For example, here Venantius has certainly noted down the key for penetrating the finis Africae. If I try thinking that the message is about this, then I am suddenly enlightened by a rhythm… Try looking at the first three words, not considering the letters, but the number of the signs … IIIIIIII IIIII IIIIIII… Now try dividing them into syllables of at least two signs each, and recite aloud: ta-ta-ta, ta-ta, ta-ta-ta… Doesn’t anything come to your mind?”
“No.”
“To mine, yes. ‘Secretum finis Africae’ … But if this were correct, then the last word should have the same first and sixth letter, and so it does, in fact: the symbol of the Earth is there twice. And the first letter of the first word, the S, should be the same as the last of the second: and, sure enough, the sign of the Virgin is repeated. Perhaps this is the right track. But it could also be just a series of coincidences. A rule of correspondence has to be found…”