Dionysius which proved to be quite successful. Dionysius was forced back into the citadel. At this time, 344 BC, Timoleon arrived and began his invasion of Sicily. Dionysius, out of respect for Timoleon and aware he no longer had a chance of victory, arranged the surrender of the citadel and was given safe passage to Corinth. Dionysius died in the following year in Corinth, where he lived in increasingly miserable conditions. In the doctrine of illumination In the Seventh Letter Dionysius II is central to the detailed description of Plato's epistemological digression, known as doctrine of illumination in secondary literature. Following his second visit to Sicily, Plato received a letter from Archytas praising the progress Dionysius II had made in philosophy. Plato visits a third time and tests Dionysius II to determine whether he had really made as much progress in philosophy as reported. According to the Seventh Letter, the authenticity of a prospective philosopher could be tested by setting out the extent of the undertaking. Those possessing a divine quality would accept the challenge, while pseudo-philosophers would find the tasks so daunting they would abandon the pursuit of wisdom. According to the doctrine of illumination, a genuine philosopher will regulate and order all daily activities to enhance learning and reason. Disclosing the true and difficult nature of philosophical life was an infallible test to separate the wheat from the chaff. Plato's view was that philosophers had to develop a resolute character while engaging in philosophical education. Those who shun hard work, needed to be rejected. When Plato disclosed the nature of philosophical pursuits and the self-discipline needed to gain insights into higher matters, Dionysius II claimed to already know the most significant aspects of Plato's teachings. In the Seventh Letter, Plato also suspects that Dionysius II had published a treatise expounding his knowledge of philosophy as teachings. By disdaining further training, Dionysius II fails Plato's test. In popular culture and literature Dionysius is one of the central characters in the legend of the Sword of Damocles. The Encyclopedia Britannica states that Dionysius I, not II, is the subject of the story "The Sword of Damocles". The anecdote apparently figured in the lost history of Sicily by Timaeus of Tauromenium (c. 356–260 BC). The Roman orator Cicero may have read it in the texts of Greek historian Diodorus Siculus. Cicero used it in his Tusculanae Disputationes, 5. 61,[1] by which