ABSTRACT
CALIGULA’S ILLNESS WAS clearly serious.1 Philo reports that news of it caused widespread consternation throughout the empire, even leading to mental distress and severe depression. Suetonius and Dio echo the same excessive reaction. Crowds slept in the open outside the imperial residence waiting for bulletins. The equestrian Atanius Secundus announced that he would fight as a gladiator, and Publius Afranius Potitus vowed publicly to give his life, if the emperor should be spared, extravagant offers but with precedents in similar vows for Augustus’ recovery.2 Some scholars have tended to agree with Philo, that the illness was some kind of nervous breakdown, caused by the stress of the first six months of the reign.3 Others have sought to diagnose a more specifically physical ailment. Among recent attempts, A.T. Sandison has suggested that Caligula may have suffered from epidemic encephalitis, which leads to symptoms of mental derangement. R.S. Katz, on the other hand, argues that he suffered from hyperthyroidism, which can be triggered by serious stress. He suggests that the strain of rule caused Caligula’s thyroid gland to become overactive, thus contributing to his breakdown. One serious problem with his thesis, however, is that hyperthyroidism is usually accompanied by exophthalmia (bulging of the eyes), which conflicts with Suetonius’ and Pliny’s description of Caligula’s eyes as hollow. V. Massaro and I. Montgomery suggest that the illness may have been a viral one that affected the central nervous system, with residual mental symptoms.4 All these, and other, speculations about the nature of the illness are in the end unprovable, and like the speculations about Caligula’s mental state rely on descriptions of symptoms that have been much distorted by the process of source transmission. Nor can we be sure that the illness had any longterm effect. The sources seem to suggest it was a turning point in Caligula’s reign, and Philo implies a causative link between it and his subsequent behaviour. But it can have played at best only a contributory role, since there is no evidence of any dramatic change in his behaviour — his serious excesses and clashes with the senate do not begin until 39.5
The precise date of the illness is also uncertain. Philo says that it fell in the eighth
month of his reign (mid October to mid November) and that news of it was brought by sailors as they returned to their home ports at the end of the sailing season, which Vegetius places at November 11.6 If the illness occurred so late it would be difficult to fit his recovery, and other events recorded for late 37, into the short remainder of the year. Also, Dio implies that Caligula fell ill not long after his first consulship, which he held up to the end of August. It could very well be that he was struck down shortly after being acclaimed pater patriae, on September 21, and that news of his progress through gradual improvement to final recovery continued to be brought by sailors right up to the end of the shipping season. There is a clue also in the calendar of Egypt. One of the honorific months introduced there by Caligula (it did not survive him) was Soter (‘Saviour’). This is known to have been the equivalent of the Egyptian Phaophi, which began on September 28.7 Soter might well have been named because during this month he began his initial recovery from illness, which should, accordingly, be placed at some point in October.
