"I can't see the future, Diana."

"But you know the past, enough to understand about Clodius and Milo. Explain it to me. If I could understand what's happening, perhaps it wouldn't worry me so much."

"Very well, Diana. Clodius and Milo: where to begin? Well, we shall have to start with Caesar and Pompey. You know who they are."

"Of course. Gaius Julius Caesar is the man Meto serves, up in Gaul. The greatest general since Alexander the Great."

I smiled. "So Meto says. Pompey might not agree."

"Pompey cleared the seas of the pirates and conquered the East."

I nodded. "And surnamed himself Magnus – 'the Great,' just like Alexander. As I said a moment ago, sometime when two men want the same thing -"

"You mean Caesar and Pompey both want to be Alexander the Great?"

"Yes, exactly, since you put it like that. And there can't be two at once. The world is not big enough."

"But don't Caesar and Pompey both serve the Senate and the people of Rome?"

"Nominally, yes. They receive their commands and permission to raise their armies from the Senate, and between them they've conquered the world in the name of the Senate. But sometimes servants outgrow their master. Caesar and Pompey have both grown too big for the Senate. So far, the salvation of the Republic has been that the two generals have held one another in check – neither can grow too powerful for fear of riling the other. And there have been other factors figured into the balance."

"Pompey married Caesar's daughter, didn't he?"

"Yes: Julia. Apparently it was a genuine love match. That marriage link smoothed over the two men's differences. Family connections mean everything, especially to patricians like Caesar. And another factor: the two rivals used to be three. There was Marcus Crassus."

"The man who owned Meto when he was a little boy. He was the one who put down Spartacus and the slave rebellion."

"Yes, but despite that victory Crassus was never much of a general. But he did manage to make himself the richest man in the world. Crassus, Caesar and Pompey formed what they called the Triumvirate, sharing power between the three of them. That seemed to work for a while. A table with three legЈ is steady."

"But a table with just two legs…"

"Sooner or later has to fall. Last spring Crassus was killed in Parthia, at the eastern end of the world, trying to prove his military prowess once and for all by conquering some of the same lands that Alexander conquered. But the Parthian cavalry defeated him. They killed his son, along with forty thousand Roman soldiers. They chopped off Crassus's head and used it for a stage prop to amuse their king. Exit Crassus."

"Leaving the Triumvirate with only two feet."

"But at least those two feet were still bound together by the marriage link between Pompey and Caesar – until Julia died in childbirth. Now nothing holds the two of them together, and there's nothing to keep them from coming to blows sooner or later. Rome holds its breath, like a hedgehog watching two eagles circle overhead, ready to battle it out to see which of them gets to eat the hedgehog."

"I think you must be the first man ever to compare Rome to a hedgehog, Papa!" Diana studied the stars. "Is there a hedgehog constellation?" "I don't think so."

"So you've told me all this about Caesar and Pompey the Great. But what about Clodius and Milo?"

"Caesar and Pompey are eagles up in the sky, soaring over mountains and seas. Down here on solid ground, it's Clodius and Milo who've been fighting over Rome itself – the city, not the empire. They fought with gangs instead of armies. Instead of mountain ranges and seas, they squabbled over the seven hills and the markets on the riverfront. Instead of battles, they staged riots in the Forum. Instead of campaigning against barbarians, they campaigned against each other for office – bullying and bribing voters, pandering to their constituents, postponing elections, pulling every possible trick to get the better of each other.

"Milo represents those who call themselves the Best People – old families, old money, the most conservative elements in the Senate. The kind of people Pompey likes to associate with, so it's not surprising that from time to time Milo has more or less acted as Pompey's henchman here in Rome.

"Clodius is-was-a radical, despite his patrician blood. He appealed to the mob. When he was in the military, he staged an uprising of common soldiers against their commander, who happened to be his own brother-in-law. The year the plebeians elected him tribune, he promised to set up a free grain dole, and he did, by annexing Cyprus to finance the scheme. Clodius was always out to better the lot of common foot soldiers and farmers and the city poor, and in return they were always there to vote when he needed them, sometimes with ballots, more often with fists. The rabble loved him. And the Best People hated him.

"From time to time Clodius found himself on the same side as Caesar, another patrician with populist leanings, and so they assisted each other, mostly behind the scenes. People came to think of them as allies – Caesar and Clodius against Pompey and Milo. The two great men moving all over the world, each allied with a lesser man with a gang at his disposal here in Rome to fight for control of the capital."

"Like the heroes of the Iliad," said Diana. "The gods allied with mortals: one god looking out for Hector, another god on the side of Achilles. And Hector and Achilles each haying an army."

"All these references to Troy – I take it you've been reading Homer?"

"I need to practise my Greek. Mother helps me." "Your mother can't read."

"Yes, but she speaks Greek. She helps me with pronunciation."

"I see. Well, a little literary allusion goes a long way. But if I can compare Rome to a hedgehog, I suppose we can also compare our local gang leaders to Hector and Achilles. It's apt, in a way. The gods withdrew their favour from Hector in the end, didn't they? So fell the House of Priam, and Troy along with it. The gods can be fickle, like any ally; it's all politics in the end. Allegiances shift like sand underfoot. Loyalty slips through your fingers."

"And a man dies."

"Yes. Then more men die, usually."

"And buildings burn."

We watched the Forum in silence for a while.

"Caesar and Pompey, Clodius and Milo," said Diana. "Still, how did it come to this, Papa? The Senate House burned to the ground…"

I sighed. The young think there must always be a simple answer. "You know how the elections are held, Diana, or at least how they're supposed to be held: citizens gather on the Field of Mars to cast their ballots for the various magistrates who run the government. There are different elections, on different days, for the various magistrates. Most of the elections are held in the summer; good weather for gathering out of doors. The voters elect two consuls, who have the highest power. After the consuls come the praetors, and then the aediles and the quaestors and so on, all with different powers and duties.

"The old year ends. At the beginning of Januarius the elected magistrates take office. They serve for one year and then step down or move on to govern foreign provinces. So it's been, for hundreds and hundreds of years, going all the way back to the fall of the kings and the founding of the Republic.

"That's how it's supposed to work, anyway. But today Rome is a city without magistrates. We're halfway through the month of Januarius, and still there are no magistrates to run the state."

"What about the tribunes?" said Diana.

I hummed, stalling while I thought of the answer. The Roman constitution is so damnably complicated! "Technically, tribunes are not magistrates. The tribunate was established long ago when only patricians could be magistrates, and the plebeians demanded to have their own representatives. Nowadays the magistracies are open to both classes, but tribunes must still be plebeians. There are ten of them each year, chosen by a special assembly of plebeians only. They still tend to represent the interests of the weak against the strong, the poor against the rich. Clodius himself served a term as tribune – that was the year he managed to get Cicero sent into exile and established the grain dole."