"I wasn't ridiculing," I protested. "I merely asked some questions. Besides, this is not a true religion. It's a foreign cult. And no educated person, whatever his nation, should lend credence to such fraudulent drivel."

"So what? She is a princess, and certain allowances are always made for royalty. It's not as if this were Rome and Ataxas were challenging Jupiter for supremacy."

In such deep theological discussion did we pass the time as our bearers sweated our way to the Museum. The litter lurched a bit as they carried us up the great stairway; then they deposited us in the anteroom of the dining hall. There we were greeted by the luminaries of the place. Which is to say that they groveled to Berenice and graciously acknowledged us as part of her entourage.

We passed into the refectory, which had been laid out for a banquet suitable for scholars, which is to say simple, austere and elegant. But the presence of royalty improved matters. The wine was first-rate, as was the food, although ostentatious sauces and bizarre presentation were out. For entertainment, a lengthy passage from Homer was recited by Theagenes, the greatest tragic actor of the Alexandrian theater. We all sat through this with becoming dignity. The excellent wine helped.

In fact, the general air of quiet and self-possession made me a bit suspicious. Something seemed to be missing. Then I noticed that Iphicrates of Chios wasn't there. I turned to Amphytrion.

"Where's old Iphicrates? He's missing a good feed and he might liven things up a bit."

The Librarian looked slightly pained. "He was in his study this afternoon. Perhaps I should send to see that all is well with him." He summoned a slave and sent him off to check on Iphicrates. The old man couldn't come right out and say that he was overjoyed with Iphicrates's absence.

I knew that the after-dinner chat would consist entirely of learned discussion, and this I wished to avoid at all costs. If I couldn't get away, the best I could hope for was argument and vituperation. This I knew Iphicrates could supply in abundance. As the dishes were cleared away, a white-bearded old gentleman stood.

"Your Highness, honored guests, I am Theophrastus of Rhodes, chairman of the Department of Philosophy. I have been asked to lead the discussion for this evening. With your permission, I have chosen as subject the concept first articulated by the Skeptic philosopher Pyrrho of Elis: acatalepsia. That is to say, the impossibility of knowing things in their own nature."

This was even worse than I had feared. The slave reappeared and whispered something urgently to Amphytrion, at which a look of great consternation crossed the Librarian's face. He stood hurriedly.

"I am afraid I must interrupt the evening's festivities," he said. "It seems there has been some sort of-of accident. Something has happened to Iphicrates and I must go see what is wrong."

I turned and snapped my fingers. "My sandals." Hermes slipped them on my feet.

"Sir," Amphytrion said, "it is not necessary for you to-"

"Nonsense," I said. "If there is trouble, I wish to be of any assistance I may." I was desperate to get out of there.

"Very well, then. Esteemed Theophrastus, please continue."

We left the dining hall with the old boy's voice droning away behind us. The Museum was strangely dark and quiet at night, with its small slave staff gone off to their quarters, except for a boy whose sole task was to keep the lamps filled and trimmed.

"What seems to have happened?" I asked the slave who had been sent to find Iphicrates.

"You'd better see for yourself, sir," he said, sweating nervously. Slaves often get that way when something bad has happened. They know that they are most likely to be blamed. We crossed the courtyard where I had seen the workmen assembling Iphicrates's model canal mechanism the day before. It looked unreal in the moonlight. The slave stopped outside the study where we had seen his drawings.

"He's in there."

We went in. Six lamps provided decent illumination, enough to see that Iphicrates lay on his back in the middle of the floor, dead as Hannibal. A great vertical gash divided his lofty brow almost in two, from the bridge of his nose to his hairline. The room was a shambles, with papers scattered everywhere and cabinets thrown open, their contents adding to the mess on the floor.

"Zeus!" Amphytrion cried, his philosophical demeanor slipping a bit. "What has happened here?"

"For one thing," I said, "there has been no accident. Our friend Iphicrates has been most thoroughly murdered."

"Murdered! But why?"

"Well, he was rather an abrasive sort," I pointed out.

"Philosophers argue a great deal," Amphytrion said stiffly, "but they do not settle their arguments with violence."

I turned to the slave, who still stood without the door. "Go and bring the physician Asklepiodes."

"I think it is somewhat too late even for his skills," Amphytrion said.

"I don't require his healing skills, but his knack for reading wounds. We have worked together on a number of such cases in Rome." I went to look at the cabinets. The locked one had been pried open and its contents scattered.

"I see. But I must immediately report this incident to his Majesty. I imagine that he will wish to appoint his own investigating officer."

"Ptolemy? He'll be in no condition to hear any reports or appoint any officers until late tomorrow morning at the very earliest." I looked at the lamps. One had burned low, its wick smoking. The others flamed brightly.

"Nonetheless, I shall send word," Amphytrion said.

From without we could hear the voices of a number of people approaching. I went to the door and saw the whole mob from the banquet crossing the courtyard.

"Asklepiodes, come in here," I said. "The rest, please stay outside for the moment."

The little Greek came in, beaming all over his bearded face. He loved this sort of thing. He walked to the corpse and knelt beside it, placing his hands beneath his jaw and moving the head this way and that.

"Even the best lamplight is inadequate for really good analysis of this sort," he pronounced. "Decius Caecilius, would you place four of the lamps around his head, no more than three or four inches away?" He got up and began rooting about in the mess. I did as he requested and within a minute he found what he was looking for. He returned with what looked like a shallow, very highly polished bowl of silver. He turned to the little group of scholars who peered in through the door.

"Iphicrates was doing research on the use by Archimedes of parabolic reflectors. A concave mirror has the power to concentrate the light it reflects." He turned the open end of the bowl toward Iphicrates, and sure enough, it cast a beam of concentrated light upon the ghastly wound. From outside came murmurs of admiration at this philosophic cleverness.

While Asklepiodes made his inspection, I went to the doorway.

"Your colleague Iphicrates has been foully murdered," I announced. "I ask all of you to think whether you have seen any strange persons in this area just before the banquet." I said this primarily to keep them occupied so that they wouldn't interfere with my investigation. I wouldn't have trusted this lot to notice if their robes were on fire. Sosigenes was the only one I would have thought a reliable observer. Except for the late Iphicrates, who was unavailable for comment.

Fausta came close and peered in. "A murder! How thrilling!"

"If you really marry Milo," I said, "murders will get to be old stuff to you, too." I turned back to Amphytrion. "Is there any sort of inventory of Iphicrates's things? It would help greatly to know what is missing, since the murderer or murderers clearly were looking for something."

He shook his head. "Iphicrates was a secretive man. Nobody but he knew what he possessed."