The city of Luni, which is now destroyed, was very ancient, and we find from the stones of Troy, that from the city of Luni there went a fleet and soldiers in aid of the Greeks against the Trojans; afterwards it was destroyed by soldiers from beyond the mountains, by reason of a lady, the wife of a lord, who, when on the way to Rome, was adulterously seduced in this city of Luni, wherefore, as the said lord returned, he destroyed the city by force, and to-day the country is desert and unhealthy. And note that of old the coasts were much inhabited, and albeit inland there were few cities, and few inhabitants, yet in Maremma and Maretima, towards Rome on the coast of the Campagna, there were many cities and many inhabitants, which to-day are consumed and brought to nought by reason of the corruption of the air: for there was the great city of Populonia, and Soana, and Talamone, and Grosseto, and Civitaveglia, and Mascona, and Lansedonia, which were with their troops at the siege of Troy; and in Campagna, Baia, Pompeia, Cumina, and Laurenza, and Albania. And the cause why to-day these cities of the coast are almost without inhabitants and unhealthy, and also why Rome is less healthy, is said by the great masters of astronomy to be because of the movement of the eighth sphere of heaven, which in every hundred years moves one degree towards the North Pole, and thus it will move 15 deg. in 1,500 years, and afterwards will turn back in like manner, if it be the pleasure of God that the world shall endure so long; and by the said change of the heaven is changed the quality of the earth and of the air, and where it was inhabited and healthy, it now is without inhabitants and unhealthy, and also the converse. And furthermore, we see that in the course of nature all things in the world change, and rise and diminish, as Christ said with His mouth that nothing here abides. Secs. 51-56.--_Of Viterbo, Orvieto, Cortona, Chiusi, Volterra, and Siena._ Sec. 57.--_The story returns to the doings of the city of Florence, and how S. Miniato there suffered martyrdom under Decius, the Emperor._ [Sidenote: 270 A.D.] [Sidenote: 1013 A.D.] [Sidenote: Purg. xii. 100-105.]