If we except the south-western coast and the district about Leontini, Sicily is altogether a mountainous country. Mount Aetna is the real central knot of the island, and the highest mountains proceed from it in a north-eastern direction as far as cape Pelorus just opposite to Italy. The Heraean range likewise proceeds from Aetna in a western direction, while another chain extends southwards. This last range is considerably lower than the others, but still high enough to form the watershed between the eastern and western coast. In the part between Palermo and Messina, the mountains approach very close to the coast, so that often two places situated on the coast are not connected by a road, just as is the case in many parts of Liguria. Hence, during the wars of the Romans, we never find that the northern coast formed their scene of operation, which it is in all the wars on the south coast, for in this latter part there are roads, and armies can move. But on the northern coast there never was any communication either in the Punic wars or in those of the middle ages and modern times. It is of importance to know this in order to understand the history of the first Punic war. AETNA is the highest mountain both of Italy and Sicily; it had only very few eruptions in antiquity, but they were sometimes of a violence which has never been equalled in modern times. According to Thucydides, the third eruption, after the settlement of the Greeks in Sicily, occurred in his own days, in the time of the Peloponnesian war. We need not, however, scrupulously insist on this number, for it is possible that all the eruptions were not recorded, and that there had been some at a time when no annals were yet kept. The eruptions of which we know, belong to Olympiads 70, 82,[60] and Olymp. 88, 3, or the sixth year of the Peloponnesian war. The greatest subsequent eruption in ancient times occurred after the death of Caesar. A still more terrible one is recorded by the earliest Byzantine writers of the age of the Greek emperor Anastasius or Zeno. During the eruption in the age of Caesar, the ashes are said to have been thrown as far as Peloponnesus and Africa, which is probably no exaggeration; but it seems scarcely possible that, in the reign of Anastasius, the ashes should have been carried as far as Constantinople, though it certainly is very difficult positively to assert anything about these powers of nature. ERYX (monte S. Giuliano), situated in an isolated position on the western promontory, is a mountain of great historical interest. It is high, but a tame mountain, and is celebrated for its temple of Venus Erycina; but it has been immortalised in history by the defence of Hamilcar Barcas, who was blockaded there by the Romans for years, and maintained himself in spite of all difficulties: that defence is one of the greatest events in military history.