The canny senators, suspecting that he might forget his promises, ruled that the speech should be recited annually (it looked like a tribute to the new ruler’s oratory: in reality it was an attempt to hold him to his pledge of good behaviour).

Even so most of the ancient accounts of Caligula’s reign focus on his cruelty, his excesses and (following Suetonius, who wrote the classic biography of the emperor almost a hundred years after his death) his clinical insanity – an unpredictable mixture of fits, anxiety, insomnia and hallucinations. A whole range of stories tell how he claimed to be a god, to hold conversations with Jupiter and to sleep with the moon goddess. He is said to have built a bridge to link his palace on thePalatine hill with the major temples on the nearby Capitoline hill, as if to unite secular and religious power in the state. There is also plenty of talk about his ridiculously extravagant lifestyle (from serving food covered in gold leaf to draping his wife in jewellery that was worth a good deal more than the total fortune of the average Roman senator) and, of course, about his capricious sadism. According to Suetonius, he forced a father to watch the execution of his son and then, later that day, to dine with him at the palace. (Why on earth did the man turn up to dinner? Answer: because he had another son.) He used criminals as food for his wild beasts when beef became too expensive. On one occasion,