The Rule of Four

He also made a meal of cardiac anatomy, Charlie continued.

There's no septum? Paul said, as if he knew what Charlie meant.

There is. There just aren't any pores in it.

What's a septum? I asked.

The wall of tissue between the two sides of the heart. Charlie walked over to Paul's book and flipped through it to find a diagram of the circulatory system. Galen got it all wrong. He said there were little holes in the septum where blood passed between the chambers.

There aren't?

No, Paul snapped, beginning to sound as if he'd been working on this longer than I thought. But Mondino made the same mistake about the septum. Vesalius and Servetus figured it out, but not until the mid-1500s. Leonardo followed Galen. Harvey didn't describe the circulatory system until the 1600s. This riddle is from the late 1400s, Charlie. It has to be the rete mirabile or the septum. No one knew that air mixed with blood in the lungs.

Charlie chuckled. No one in the West. The Arabs figured it out two hundred years before your guy wrote his book.

Paul began rifling through his papers. Thinking the matter was settled, I turned to go. I gotta run. I'll see you guys later.

But just as I moved toward the hallway, Paul found what he'd been looking for: the Latin he'd translated weeks earlier, the text of Colonna's third message.

The Arab doctor, he said. Was his name Ibn al-Nafis?

Charlie nodded. That's the one.

Paul was all excitement. Francesco must've gotten the text from Andrea Alpago.

Who?

The man he mentions in the message. Disciple of the venerable Ibn al-Nafis. Before either of us could speak, Paul was talking to himself. What's Latin for lung? Pulmo?

I made for the door.

You're not going to wait to see what it says? he asked, looking up.

I'm supposed to be at Katie's in ten minutes.

This'll only take fifteen. Maybe thirty.

I think it occurred to him only at that moment how much things had changed.

I'll see you guys in the morning, I said.

Charlie, who understood, smiled and wished me luck.

It was a signal night for Paul, I think. He realized he'd lost me for good. He also sensed that no matter what Colonna's final message was, it couldn't possibly contain the man's entire secret, when so little had been revealed in the first four parts. The second half of the Hypnerotomachia, which we had

always assumed was filler, must in reality contain more ciphered text. And whatever consolation Paul took in Charlie's medical knowledge, or in having solved the fifth riddle, it dissipated quickly when he saw Colonna's message and realized that he was right.

I fear for you, reader, as I fear for myself. As you have perceived, it was my intention at the beginning of this text to betray to you my meanings, no matter how deeply I wrapped them in codes. I have wished for you to find ¦what you seek, and have acted as your guide.

Now, however, I find that I have not faith enough in my own creation to continue in this manner. Perhaps I cannot judge the true difficulty of the riddles here contained, even if their creators assure me none but a true philosopher could solve them. Perhaps these wise men, too, are jealous of my secret, and have misled me so that they may steal what is rightfully ours. He is clever indeed, this preacher, with followers in every camp; I fear he turns my soldiers against me.

It is as a defense to you then, reader, that I pursue my present course. Where you have become accustomed to finding a riddle within my chapters, you will henceforth find no riddles at all, and no solutions to lead you. I will employ only my Rule of Four for the duration of Poliphilos journey, but I will offer you no suggestion of its nature. Only your intellect will guide you now. May God and genius, friend, shepherd you aright.

It was confidence alone, I think, that prevented Paul from sensing his abandonment until many days had passed. I had left him; Colonna had left him; now he navigated alone. He tried, at first, to reinvolve me in the process. We had solved so much together that he thought it would be selfish to let me absent myself in the eleventh hour. We were so close, he thought; we had so little left to do.

Then a week passed, and another. I was beginning again with Katie, re-learning her, loving her alone. So much had happened in the weeks we'd been apart that I was more than occupied trying to catch up. We alternated meals at Cloister and at Ivy. She had new friends; we had new routines. There were family matters of hers I began to take an interest in. 1 sensed that once I'd won her trust back completely, she had things she wanted to tell me.

Everything Paul had learned about Colonna's riddles, meanwhile, began to fail him. Like a body of work slowly decaying in function, the Hypnerotomachia resisted all his trusted medicines. The Rule of Four was elusive; Colonna had given no indication of its origin. Charlie, the hero of the fifth riddle, stayed up with Paul some nights, worrying about the effect my departure was having. He never asked me to help, knowing what the book had done to me once, but I saw the way he hovered over Paul, like a doctor eyeing a patient he fears is trending badly. A darkness was setting in, a book lover's heartbreak, and Paul was helpless against it. He would suffer, without my help, until Easter weekend.

Chapter 19

On the way back to Dod, I shuffle through Katie's pictures of Princeton Battlefield. In shot after shot I've caught her in midmotion, running toward me, hair streaking behind, mouth half open, her words caught somewhere in the registers of experience beyond the camera's range. The pleasure of imagining her voice in them is the joy of these pictures. In another twelve hours I'll see her at Ivy, escorting her to the ball she's been anticipating almost since we met, and I know what she'll be waiting for me to say. That I've made a choice I can stick to; that I've learned. That I won't be returning to the Hypnerotomachia.

When I get back to the room, I expect to find Paul at his desk, but his bunk is still empty, and now the books on his dresser are gone. Taped to the top of the door frame is a note, this one in large red letters.

Tom—

Where are you? Came back looking for you. Figured out 4S-10E-2N-6W! Gone to pick up topo atlas at Firestone, then down to McCosh. Vincent says he has the blueprint. 10:15.

— P.

I read the message again, piecing it together. The basement of McCosh Hall is the location of Taft's office on campus. But the last line leaves me cold: Vincent says he has the blueprint. I pick up