Maximus of Ephesus (Greek: Μάξιμος ὁ Ἐφέσιος; c. 310 – 372 AD) was a Neoplatonist philosopher. He is said to have come from a rich family, and exercised great influence over the emperor Julian, who was commended to him by Aedesius. He pandered to the emperor's love of magic and theurgy, and by judicious administration of the omens won a high position at court. His overbearing manner made him numerous enemies, and, after being imprisoned after the death of Julian, he was put to death by Valens.
The most detailed source for the life of Maximus is Eunapius in his Lives of the Sophists, but he is also referred to by Ammianus Marcellinus, the emperor Julian, and Libanius. Christian writers also discuss him, albeit in very negative terms.
Maximus was born around the beginning of the 4th century. Ammianus Marcellinus calls Ephesus the hometown of Maximus. This is doubted by some scholars, but it is certain that he originated from the west of Asia Minor. His parents were wealthy. Maximus had a brother named Claudianus, who also became a philosopher. Another brother, Nymphidianus, was appointed by emperor Julian Magister epistolarum graecarum (secretary for Greek correspondence). Ammonius Hermiae reported that Maximus was a pupil of the Neoplatonist "Hierius".
From around 335–350 Maximus was in Pergamon as a pupil of Aedesius. While he was there, Maximus studied alongside Chrysanthius, Eusebius of Myndus, and Priscus. Many Neoplatonists practiced theurgy (attempting to commune with God by special ritual actions), and there is a testimony according to which Maximus successfully breaking a love-spell which had been cast on the philosopher Sosipatra by one of her relatives.
Around 350, Maximus left Pergamon in order to work in Ephesus as a philosophy teacher. Apparently Christians also participated in his instruction: a Christian named Sisinnius, who later became a Novatianist bishop in Constantinople, is said to have studied with Maximus. In 351, the later emperor Julian went to Pergamon, in order to study with Aedesius. Whilst there, Eusebius warned Julian against getting involved with the magic arts practised by Maximus, but his warning had the opposite effect, and Julian went to Ephesus between May 351 and April 352, in order to continue his training with Maximus there.
In November 355, Julian was appointed Caesar, and Julian remained in contact with Maximus. In 361, as emperor, Julian invited Priscus and Maximus to Constantinople. The two philosophers accepted the invitation. Maximus did not let himself be deterred by unfavorable omens, but is said to have explained that it was possible to force the favour of the gods. Both Neoplatonists from then on remained near the emperor, who used them as religious-philosophical advisors and discussion partners. Eunapius states that Maximus and Priscus had no political authority, but also writes that Maximus became arrogantly inaccessible and used his influential position to personally enrich himself. Maximus travelled in the summer of 362 with Julian to Antioch, and then in March 363 on the Persia campaign. Before the emperor died on 26 June 363 from a combat injury, he held a last philosophical conversation with Maximus and Priscus.
Maximus continued to receive imperial favour under the emperor Jovian, but after Jovian's death his enemies came after him. In spring 364 he was accused of causing a lengthy illness in the new emperors Valentinian I and Valens. This accusation could not be confirmed, and was dropped. But his numerous opponents did not relent; in 365/366 he was again arrested and accused of having illegitimately enriched himself. A high fine was imposed, and he was sent "to Asia" - probably into his homeland – to find the penalty. Because he was not able to pay, he was tortured. Eunapius reported that Maximus wanted to kill himself, as he could no longer bear the pain, and his wife procured some poison. His wife drank the poison first, but Maximus then did not drink.
Later the proconsul of Asia, Clearchus, who was a supporter of the old religion, helped the prisoner. Clearchus provided for the release of the philosopher and restored a large part of his properties, which he had lost. Maximus began teaching philosophy again, and even dared to return to Constantinople.
Around 370, Emperor Valens was informed that a group of individuals had consulted an oracle to find out who the next emperor would be and were told the next emperor's name would begin with the letters Theod and that the emperor Valens would "die a strange death, and would not be given burial or the honour of a tomb". As a result, Valens, with the assistance of polytheistic philosophers, resorted to a massacre of individuals with those letters at the beginning of their names. This persecution made Valens detestable to his subjects. Eunapius indicates that Maximus was falsely implicated in the oracle plot but nonetheless was executed by Festus, the new proconsul of Asia, in 372. The next Roman Emperor was Theodosius I.
The Suda says that Maximus wrote a number of works including On Insoluble Contradictions, On Forecasts, On Numbers, and a commentary on Aristotle. Two lost commentaries are testified from other sources: one on the Categories, from which a fragment survives, and one on the Prior Analytics, to which Themistius responded. Maximus is reported to have agreed with Eusebius, Iamblichus and Porphyry in asserting the perfection of the second and third figures of the syllogism.