"Eco!" I called softly. "We've no right to be snooping here. Eco, where are you?" I wandered up and down the aisles, until I discov-ered another door at the far corner of the room. It opened into yet another office. From small windows set high in the wall came the sounds of ships knocking together in the harbor and the cry of seagulls. There was no sign of Eco inside. I backed out of the room and closed the door behind me. I took several steps before I suddenly realized what I had seen and hurried back.

On a table against one wall I saw a simple scale. Neatly stacked beside it were some sample weights of silver and gold. There was also a small wooden tub on the table. I stepped closer. Sure enough, the tub was half filled with water, and there were several waterline markings made with a piece of chalk along the inner surface.

Behind me, I heard the door close.

"I thought I bade you farewell, Gordianus." There was not the slightest hint of good humor in Dorotheus's voice. Without the beaming smile, his round, bearded face had a stern, almost menacing look; the constant smile had kept me from seeing the cold, predatory gleam in his eyes, so common in successful traders and merchants. I also realized what a large man he was. Fat, yes, but the fellow had arms like a blacksmith's-strong enough, I had no doubt, to drag the smaller, weaker Agathinus onto the stone cube, and then to push him backward onto the cruel spike.

"I'm looking for my son," I said, as innocently as I could. "Eco has a terrible habit of wandering off on his own. I really should be less indulgent…"

But Dorotheus wasn't listening. "How much, Finder?"

"For what?"

"How much to shut you up and send you on your way back to Rome?" He might be a murderer, but he was a businessman first.

If accepting his bribe meant getting safely through the door behind him, why not? But I thought of Agathinus on the night before-the final night of his life-saying, I like you, Gordianus. and I like your son… the way he laughed at Dorotheus's awful jokes…

and offering to do me the favor of showing me Archimedes's tomb. I remembered the gaping grimace of horror on his face when we found him, and I shuddered, thinking of the appalling agony he must have suffered at the end, transfixed like an insect on a pin.

"Agathinus did tell you last night about meeting me outside the Achradina Gate?" I said.

Dorotheus, deciding to submit to a bit of conversation, let his face relax. The hint of a smile returned to his lips. "Yes. He was quite looking forward to tramping through the thicket with you. I insisted on coming along for the fun."

"And Margero?"

"I'm afraid I lied to you about that, Finder. Margero excused himself as soon as Agathinus caught up with us last night. He could hardly stand dining in the same room with him, in case you didn't notice, and he was in no mood to stroll along beside him afterward. Probably Margero was in a great hurry to get home so he could get drunk in solitude and make up new poems for that silly boy at the gymnasium."

"And you?"

"I saw Agathinus home. Then I came here." "To your offices? In the middle of the night?" "Don't be coy, Finder. You saw the scale and the tub of water." "A demonstration of Archimedes's principle?" "Would you believe, I never quite grasped it, until Cicero explained it last night."

"What could be so important that you had to rush here at once to try it out?"

He sighed. "I've suspected for years that Agathinus must be cheating me. Why not? He was always smarter than me, ever since we were boys. And the smarter partner always cheats the stupider one-that's the law of business. So I always watched every transaction, always counted every piece of silver and gold we divided be-tween us. Still, I could never catch him cheating me.

"For the last shipment of goods, he talked me into taking my pay-ment in gold vessels-pitchers and bowls and such-while he took his in coin. He needed the ready money to spend on certain investments of his own, he said, and what did it matter anyway, so long as we both received the same weight? Secretly, I thought I must be getting the better deal, because worked gold is more valuable than its weight in coinage. Agathinus was counting on my own greed, you see, and he used it against me. He cheated me. The devious bastard cheated me! Last night, with Archimedes's help, I proved it."

"Proved that your gold vessels weren't made of solid gold?"

"Exactly."

"Perhaps Agathinus didn't know."

"Oh, no, he knew. After we went into the thicket and found the tomb this morning, I confronted him. He denied the deception at first-until I dragged him onto the cube and threatened to throw him on the cone. Then he confessed, and kept on confessing, with the sight of that spike to goad him. It didn't begin with this transaction! He'd been pilfering and corrupting my shares of gold for years, in all sorts of devious ways. I always knew that Agathinus was too clever to be honest!"

"And after he confessed-" I shuddered, picturing it.

Dorotheus swallowed hard. "I could say that it was an accident, that he slipped, but why? I'm not proud of it. I was angry-furious! Anger like that comes from the gods, doesn't it? So the gods will understand. And they'll understand why I had to get rid of you, as well." He reached into the folds of his tunic and pulled out a long dagger.

I coughed. My throat was bone-dry. "I thought you intended to buy my silence."

"I've changed my mind."

"But you said-"

"You never agreed, so there was never a bargain. And now I withdraw that offer."

I looked around the room for something that might equalize the situation, but saw nothing remotely resembling a weapon. The best I could do was to pick up the tub. I threw the water on him, then threw the tub, which he knocked aside. All I managed was to make him furious and dripping wet. All trace of the laughing, genial dinner companion of the previous night had vanished. Seeing his face now, I would not have known him.

It was at that moment that the door behind him gave a rattle and burst open.

Cicero entered first, followed by a troop of well-armed Roman peacekeepers who surrounded Dorotheus at once and took his dagger. Eco trailed behind, leaping in the air in great excitement, the anxious look on his face turning to jubilation when he saw that I was unharmed.

"Eco fetched you?" I said.

"Yes," said Cicero.

"You heard Dorotheus confess?"

"I heard enough."

Eco opened his mouth wide and moved his lips, but managed only to produce a stifled grunt.

"What's the boy trying to say?" asked Cicero. "I think it must be 'Eureka! Eureka!'"

"Greed!" I said to Eco the next morning, as we made ready to vacate our room at Cicero's house. "Last night I read that idyll of Theocritus,

the poem that Cicero quoted from at dinner the other night. The poet certainly got it right:

Men no longer aspire to win praise for noble deeds,

but think only of profit, profit, profit.

Clutching their coinbags, always looking for more,

too stingy to give away the tarnish that comes off their coins!

"Thanks to greed, Agathinus is dead, Dorotheus awaits trial for his murder, and Margero the poet has lost both of his patrons in one stroke, which means he'll probably have to leave Syracuse. A disaster for them all. It's very sad; enough to make a man want to leave behind the grubby human cares of this world and lose himself in pure geometry, like Archimedes."

We gathered up our few belongings and went to take our leave of Cicero. There was also the matter of collecting my fees, not only for finding Archimedes's tomb, but for exposing Agathinus's killer.

From the atrium, I could hear Cicero in his office. He was dictating a letter to Tiro, no doubt intending for me to deliver it when I got back to Rome. Eco and I waited outside the door. It was impossible not to overhear.