Plotinus’ innermost circle includes Porphyry, Amelius Gentilianus of Tuscany, the Senator Castricius Firmus, and Eustochius of Alexandria, a doctor who has devoted himself to learning from Plotinus and will attend to him until his death.

Other students include Zethos, an Arab by ancestry who dies before Plotinus, leaving him a legacy and some land in Campania; Zoticus, a critic and poet; Paulinus, a doctor of Scythopolis; and Serapion from Alexandria.

Plotinus has had students among the Roman Senate beside Castricius, such as Marcellus Orontius, Sabinillus, and Rogantianus.

Women are also numbered among his students, including Gemina, in whose house he has lived during his residence in Rome, and her daughter, also Gemina; and Amphiclea, the wife of Ariston the son of Iamblichus.

Finally, Plotinus is a correspondent of the philosopher Cassius Longinus.

At one point Plotinus had attempted to interest Gallienus in rebuilding an abandoned settlement in Campania, known as the 'City of Philosophers', where the inhabitants would live under the constitution set out in Plato's Laws.

An Imperial subsidy is never granted, for reasons unknown to Porphyry, who reports the incident.

Porphyry, the chief disciple, critic, promoter, and biographer of the late Neoplatonist philosopher Plotinus, publishes his master’s fifty-four essays posthumously in 301, arranging them in 6 sections of 9 essays each, calling them the Enneads (“The Nines”).

Influenced by Pythagorean, Peripatetic, and Stoic ideas, the Enneads defend Plato and Platonism against the criticisms of Aristotle, but in so doing embrace a number of Aristotle's own concepts.

Plotinus repeatedly demonstrates the inadequacy of Aristotle's categories and logic to account for the whole of reality—both the things known by the senses and those known by the intellect.

Plotinus agrees with the skeptics that knowledge is essential in comprehending the Platonic forms that are "beyond" the physical heavens.

He argues, however, that, as humans possess knowledge, souls must somehow acquire it by journeying to this "transcelestial" place to see the forms there.

The reasons for the Diocletian persecution, which had begun in February 303, are uncertain, but various explanations have been advanced.

One is the possible influence of Galerius, a fanatic follower of the traditional Roman religion.

Another is the desire to restore complete unity, without tolerance of a foreign cult that is seen as separatist and of men who are forming a kind of state within the state; yet another is the influence of anti-Christian philosophers such as Porphyry and governors such as Hierocles on the scholarly class and on the imperial court.

Other explanations posit the fear of an alienation of rebellious armies from emperor worship; or perhaps the disturbances provoked by the Christians themselves, who are agitated by doctrinal controversies.

At any rate, some or all of these factors have led Diocletian to publish the four edicts of 303-304, promising all the while that he will not spill blood.

His vow goes unheeded, however, and the persecutions spread through the empire with an extreme violence that does not succeed in annihilating Christianity but causes the faith of the martyrs to blaze forth instead.

In one instance, the Christian twin brothers Cosmas and Damia, who reportedly practice medicine without accepting payment and hence become known as the "silverless ones," are supposedly martyred in Syria during the persecutions.

Maximian’s monumental bathing complex in Rome, completed in 305 and known as the Baths of Diocletian, is the largest of all Roman baths, covering an area of over one hundred and thirty thousand square yards (one hundred and eight thousand seven hundred square meters).

An arcaded enclosure wall with alternating apsidal and rectangular rooms, originally decorated with mosaics and enclosed gardens, enormous sculptures, and a theaterlike rotunda where visitors can view athletic events, surrounds the complex’s barrel-vaulted core.

Like the Baths of Caracalla, the bathing pools in the central building consist of a “caldarium” (hot bath), “tepidarium” (warm bath), “frigidarium” (cold bath), and “natatio” (swimming pool), flanked by numerous service rooms and exercise grounds.

Neoplatonist philosopher Porphyry dies in 305, probably in Rome, leaving in addition to his important writings on the life and philosophy of his mentor Plotinus voluminous scholarly writings on philosophy, religion, philology, and science.

Among these are commentaries on Aristotle's Categories, including his influential introduction (“Isagoge”), and his fiercely critical Against the Christians.

A lecturer on Plotinus and tutor to the Syrian philosopher Iamblichus, Porphyry had written a biography of the mathematician Pythagoras, and transmitted valuable fragments of earlier thought in his On Abstinence, a case for vegetarianism.