This unfortunate business at least provided me with di Pietro’ s mailbag, which turned out to be far more interesting than even I had hoped. For not only did it include the letters being sent to the radicals, it also contained another, unmarked in any way, which came from a different and unknown source. I only looked at it because I remembered the habits that Thurloe had inculcated into his office, one of which was that when examining a mailbag for suspicious correspondence, check everything else it contains as well. There were twelve letters in all, one from the radicals, ten entirely innocuous and concerned only with trading matters, and this one. Its lack of address alone would have alerted my attention, the fact that the seal on the back was entirely blank merely added to my determination. I only wished that little Samuel Morland had been there by my side, for no man was ever swifter at removing a seal, nor better at putting it back unnoticed. My own efforts were more laborious, and I cursed mightily as I wrestled with that most delicate task. But I did it, and did a fine job, so that once it was battered a little by transporting, I felt sure no one would see my handiwork.
And it was worth the effort. Inside was as fine a piece of coding as I had ever seen—a very long letter of about twelve thousand characters, in the complicated random cipher I described earlier. I felt a tingling of excitement as I contemplated it, for I knew it to be a challenge worthy of my skill.
But at the back of my mind was a more worrying thought, for ciphers are like music and have their own rhythms and cadences. This one, as I scanned it, sounded in my mind as being familiar, like a tune heard once before. But I could not yet place the melody.
Many times have men asked me why I took up the art of decipherment, for it seems to them to be a vulgar occupation, not in keeping with my position and dignity. I have many reasons, and the fact that I enjoy it is but the least of them. Men like Boyle are absorbed by teasing out the secrets of nature, in which I also take the greatest pleasure. But how wonderful it is also to penetrate the secrets of men’s minds, to turn the chaos of human endeavor into order and bring the darkest deeds from night into daylight. A cipher is only a collection of letters on a page; this I grant. But to take that confusion and turn it into meaning through the exercise of pure reason provides a satisfaction which I have never managed to communicate to others. I can only say that it is not unlike prayer. Not vulgar prayer, in which men chant words while their minds are elsewhere, but true prayer, so complete and profound that you feel the touch of God’s grace on your spirit. And I have often thought that my success shows His favor, a sign that what I do is pleasing to Him.
The letter sent by the sectaries was pathetically easy to unravel, and scarcely interesting; had I known what it contained I would never have bothered as it was not worth di Pietro’s life or the trouble his murder caused me. It spoke of preparations in that pompous language so beloved of sectaries, and referred elliptically to a place I confidently identified as Northampton. But there was little meat, nothing which justified the risk I had taken. If that lay anywhere, it was in the last, mysterious letter; I was determined to read it, and knew I must have the key.
Matthew came to me as I sat at my desk, the unreadable letter in front of me in all its defiance, and asked whether he had done well.
“Very well,” I told him. “Very well indeed, although largely by chance—your letter is uninteresting; it is this other one which fascinates me.” I held it up for him to examine, which he did with his habitual neatness and care.
“You know this already? You have unraveled it all?”
I laughed at his faith in me. “A different letter, a different source and, no doubt, a different addressee. But I know nothing and have unravelled less. I cannot read this letter. The code is based on a book, which determines the sequence of the cipher.”
“That I do not know, and unless I can find out, I will understand nothing. But I am sure it is important. This sort of code is rare; I have come across it only a few times, and then written by men of the highest intelligence. It is too complex for fools.”
“You will succeed,” he said with a smile. “I am sure of that.”
“I love you for your confidence, my boy. But this time you are wrong. Without the key, the door will remain locked.”
“So how do we find this key?”
“Only the person who wrote it, and the person who will read it, will know what it is and have a copy.”
“So we must ask them.”
I thought he was joking and began to reprove him for his levity, but I saw in his face that he was quite serious.
“Let me return to Smithfield. I will tell them that there was an attempt to steal the letter which failed. And I will offer to go myself on the boat, to guard it and ensure it comes to no harm. Then I will discover to whom this one is sent, and what is the key.”
The mind of youth sees in such a simple and direct way that I could hardly conceal my amusement.
“Why do you laugh, doctor?” he asked, his brow furrowing. “What I say is right. There is no other way of discovering what you need to know, and you have no one else to send.”
“Matthew, your innocence is charming. You would go, you would be discovered and all would be lost, even if you escaped unharmed. Do not bother me with such foolishness.”
“You treat me always like a child,” he said, saddened by my remark. “But I can see no reason for it. How else can you discover what this book is, and who it is sent to? And if you cannot trust me, who else can you send?”
I took him by the shoulders and looked into his angry eyes. “Do not be upset,” I said, more gently. “I spoke as I did not out of contempt, but concern. You are young, and these are dangerous people. I do not wish you to come to harm.”
“I thank you for it. But I desire nothing more than to do something of value for you. I know my debt to you and how little I have repaid it. So please, sir, give your permission. And you must decide fast; the letters must be returned, and the boat leaves tomorrow morning.”
I paused, and studied his fair face, its perfection spoiled by his resentment, and knew from the sight more than from his words that I would have to loosen the bonds, or lose him forever. Still, I tried one more time.
“ ‘If I be bereaved of my children, I am bereaved’ “ (Genesis 43:14).
He looked at me gently, and with such kindness; I remember it still.
“ ‘Provoke not your children to anger, lest they be discouraged’ “ (Colossians 3:21).
I bowed to that, and let him go, embracing him as he left, and watching from my window as he walked down the street outside, until he was lost from sight in the crowds. I saw the spring in his step, and the joy in his walk that came from his freedom, and I grieved over my loss. I spent the afternoon in prayer for his safety.