"As is only logical," said Dio irritably, "given that philosophers strive for lucidity, while the priests of Cybele make a religion of mystifying the senses."

"And yet our host's young daughter perceived the truth at a glance," said Trygonion.

"A beautiful girl," said Dio softly, wrinkling his brow. "Such insight on the part of a child seems almost preternatural, don't you think, Gordianus?" Trygonion looked at me shrewdly. "Perhaps your daughter is a witch."

Dio scowled and shifted uneasily, but I decided to indulge the gallus's sense of humor rather than take offense. "Diana's mother grew up in Egypt, which has many eunuchs. Diana was born with Egypt in her blood, so I suppose she knows a eunuch when she sees one. I'd like to take credit for her cleverness, but certain insights definitely come from her mother."

"Perhaps they are both witches," said Trygonion.

"Enough of your rudeness," growled Dio. "These galli think they can say anything and behave however they choose, under anyone's roof. They have no shame."

"That's not all we lack," said Trygonion with a straight face.

Whatever the source of her insight, Diana had also put her finger on the more perplexing mystery that lay beyond the thin disguises of my guests: what were they doing together? It was clear that they had no love for each other.

"If you've had enough wine," I said, knowing that Trygonion had drunk more than his share while Dio had barely touched his cup, "and if we've talked enough of your disguises, perhaps we should speak of more serious things. Why have you come to me, Teacher, and what do you want from me?"

Dio cleared his throat. "You spoke a moment ago of what you Romans call 'the Egyptian situation.' I take it, then, that you know of the false will of King Alexander, the schemes of Caesar and Pompey to get their hands on the wealth of Egypt, the wholesale murder of my colleagues who have come to seek justice from the Senate of Rome -"

I raised my hand. "Perhaps you should begin at the beginning and explain to me each step that brought you to my door. But to start, I want only the simplest answers to two simple questions. First: why have you come to me?"

Dio looked at me for a long moment, then gazed into the flames of the brazier. His voice trembled. "I have come to you because there is no one else in all Rome to whom I can turn for help, no one else I can trust-if indeed I can trust even you."

I nodded. "And second: what do you want from me, Teacher?"

"I want you to help me to-" He choked on the words. He turned his gaze from the brazier to me, so that I saw the flames dancing in his eyes. His jaw quivered and the fleshy folds of his neck shook as he swallowed hard. "Help me. Please! I want you to help me to…"

"To help you do what?"

"Stay alive!"

With his great mane of dark hair, his towering physique (not yet gone to fat), and his amiable manner, the philosopher Dio had been a conspicuous figure in the Alexandria of my youth. Like most of the upper class of Egypt, Dio was of Greek blood-with a touch of the Scythian, he had claimed, to account for his height, and a bit of the Ethiop to account for his dark complexion. He had been a familiar sight on the steps of the library attached to the Temple of Serapis, where philosophers met to debate one another and instruct their pupils.

As a young man I had ended up in Alexandria after a long journey and had decided to stay there for a while. That was where I met my future wife, Bethesda, or more precisely, where I purchased her; she was a slave offered for sale at the great slave market, very young and very beautiful. (And a troublemaker, the auctioneer had begrudgingly admitted, which was why I was able to afford her; but if what she gave me was trouble, I only craved more of it.) Thus I passed the hot Alexandrian nights in a haze of lust; and during the day, while Bethesda kept herself busy in my shabby little apartment or went to the market, I gravitated to the library steps and sought out Dio. 1 was no student of philosophy- I lacked the money for formal education-but it was a tradition among Alexandrian philosophers to engage common men in conversation from time to time, at no charge.

Now, thirty years later, I could recall only bits and pieces of those conversations, but I vividly remembered how Dio had fanned my youthful passion for truth into white-hot flames with his rhetorical conundrums, just as Bethesda had fanned my other passions. In those days I had everything I needed, which for a young man is not much: an unfamiliar city to explore, a partner in my bed, and a mentor. We do not forget the cities, or the lovers, or the teachers of our youth.

Dio was attached to the Academic school. His mentor was Antiochus of Ascalon, who in a few years would become the head of the Academy; Dio was one of the great philosopher's leading proteges. In my ignorance I once asked Dio where the Academy was, and he laughed, explaining that while the name originated from a specific site – a grove near Athens where Plato taught-it applied nowadays not to any par-ticular place or building, but to a discipline, a school of thought. The Academy transcended borders; kings might be its patrons, but they had no hegemony over it. The Academy transcended language (though of course all great works of philosophy, including those of the Academics, are written in Greek). The Academy embraced all men, and yet belonged to none. How could it be otherwise with an institution dedicated to discovering fundamental truths?

How does a man know what he knows? How can he be sure of his own perceptions, let alone those of others? Do the gods exist? Can their existence be proven? What is their form and their nature, and how can men discern their will? How can we determine right and wrong? Can right action lead to an evil result, or wrong action to a good outcome?

To a young Roman, barely twenty, in an exotic, teeming metropolis like Alexandria, these were heady questions. Dio had studied them all, and his quest for knowledge was a profound inspiration to me. Dio was hardly more than ten years my senior, but to me he seemed infinitely wise and worldly. In his presence I felt quite out of my depth, and I was immensely flattered that he would take the time and effort to explain his ideas to me. Sitting on the steps of the library while his slaves shaded us with parasols, we would discuss the differences between intellect and sensation, range the senses in order of reliability, and consider the specific ways that men depend upon logic, smell, taste, sight, hearing and touch to make sense of the world.

Thirty years had passed. Dio had changed, of course. He had seemed old to me then, but now he truly was old. The mane of dark hair had turned to silver. His belly had grown big and his skin had grown loose and wrinkled. But his broad back was unstooped. Unused to having his arms covered, he pulled up the sleeves of his stola to reveal a pair of muscular forearms as brown and weathered as his hands. He looked as healthy as myself, and given his size and robustness, he was probably stronger.

You'd be a hard man to forget,

I had told him. Now, as he implored me to help him stay alive,

I almost said,

You look like you'd be a hard man to kill.

Instead, after a considerable pause, I changed the subject. "What I find surprising, Teacher, is that you should remember me after all these years. I was your pupil only in the most casual way, and my time in Alexandria was relatively brief. After I left, I heard that your mentor Antiochus succeeded Philo as head of the Academy; your life must have become very busy after that, conversing with kings, playing host to diplomats, advising the great and powerful. How curious, that you should remember making the acquaintance of a footloose young Roman who liked to loiter on the library steps, eavesdropping on the discourses of his elders and occasionally daring to converse with them."