Plotinus is not only the greatest and most celebrated of the Neo-Platonists, he is also the first respecting whose opinions we have any authentic information, and therefore the one who for all practical purposes must be regarded as the founder of the school. What we know about his life is derived from a biography written by his disciple Porphyry. This is a rather foolish performance; but it possesses considerable interest, both on account of the information which it was intended to supply, and also as affording indirect evidence of the height to which superstition had risen during the third century of our era. Plotinus gave his friends to understand that he was born in Egypt about 205 A.D.; but so reluctant was he to mention any circumstance connected with his physical existence, that his race and parentage always remained a mystery. He showed somewhat more communicativeness in speaking of his mental history, and used to relate in after-life that at the age of twenty-eight he had felt strongly attracted to the study of philosophy, but remained utterly dissatisfied with what the most famous teachers of Alexandria had to tell him on the subject. At last he found in Ammonius Saccas the ideal sage for whom he had been seeking, and continued to attend his lectures for eleven years. At the end of that period, he joined an eastern expedition under the Emperor Gordian, for the purpose of making himself acquainted with the wisdom of the Persians and Indians, concerning which his curiosity seems to have been excited by Ammonius. But his hopes of further enlightenment in that quarter were not fulfilled. The campaign terminated disastrously; the emperor himself fell at the head of his troops in Mesopotamia, and Plotinus had great difficulty in escaping with his life to Antioch. Soon afterwards he settled in Rome, and remained there until near the end of his life, when ill-health obliged him to retire to a country seat in Campania, the property of a deceased friend, Zêthus. Here the philosopher died, in the sixty-sixth year of his age. Plotinus seems to have begun his career as a public teacher soon after taking up his residence in Rome. His lectures at first assumed the form of conversations with his private friends. Apparently by way of reviving the traditions of Socrates and Plato, he encouraged them to take an active part in the discussion: but either he did not possess the authority of his great exemplars, or the rules of Greek dialogue were not very strictly observed in Rome; for we learn from the report of an eye-witness that interruptions were far too frequent, and that a vast amount of nonsense was talked.[408] Afterwards a more regular system of lecturing was established, and papers were read aloud by those who had any observations to offer, as in our own philosophical societies.