PLOTINUS

(b. ca. a.d. 204; d. southern Italy, a.d. 270)

philosophy.

Plotinus’ family is unknown, but his education and culture were entirely Greek. He may have been born in Egypt; he studied philosophy at Alexandria and later taught it at Rome, where he settled about 243. A biography by his disciple Porphyry is informative about his manner of teaching and contains a reliable chronological list of his writings. His works were published shortly after his death in the form of six books, called Enneads because each contained nine tracts.

The contribution of the Enneads to scientific thought is minimal. They represent a combination, which is for the most part original and which is the broad meaning of Neoplatonism, of personal mysticism and a special interpretation of Plato’s metaphysics. In this interpretation there is an ineffable One, which is known only by mystical union with it, and two lower levels of reality (“hypostases”): Intellect, which is also the realm of the Platonic Ideas; and then Soul, which also contains nature. Each hypostasis is a reflection or, as it is often called, an “emanation,” of the one before it. Until modern times Neoplatonism was taken as the accepted philosophical meaning of Plato. But Plato’s interest, as it is shown by the Timaeus, in natural science for its own sake, and above all in the application of mathematics to it, is not shared by Plotinus. And his Neoplatonic successors in Athens and Alexandria, whose learning was transmitted to the Arabs in the sixth century, turned to Aristotle rather than to Plotinus for their physics.

By historical standards—or the standards of Greek science—Plotinus’ model of scientific explanation was backward-looking. The reason was his metaphysical theory of nature, which was in effect a kind of panpsychism. Matter as such was unreal, so that the properties of nature fell under the same type of explanation as those of conscious behavior; there was no discontinuity in the chain of being. Such a type of explanation is represented by the concept of sympathies, which Plotinus used not merely to explain psychophysical interaction, such as one’s awareness of a pain in his foot, but also to explain external sense perception: there is no need, he argued, for a medium such as air or light between sense organ and object (Enneads IV, 5). Sympathy was a Stoic concept; but according to Stoics it operated by mechanical means—exactly the explanatory mechanism that Plotinus rejected.

In a more general and more indirect way Plotinus’ metaphysics may have helped later scientists to recognize the importance of mathematics. For Neoplatonists, light was the visible manifestation of goodness and of power; effects of causes could be described as their “reflections” and knowledge as “illumination.” If this belief is combined with the fact, well-known since Euclid, that the behavior of light seems to follow the laws of geometry, it can be thought both to prompt further study of optics and astronomy and to justify the place of geometry in nature. Thus for Robert Grosseteste light was not only an analogy of the divine light but also the first form possessed by a physical solid. But it must be borne in mind that Plotinus’ writings were unknown in the Middle Ages, and the chief intermediary would have been St. Augustine, who was not interested in mathematical science.

The Enneads were first printed in a Latin translation by Marsilio Ficino 1492 and the Greek text in 1580. They were then of interest to humanists and philosophers, although through Ficino the tract on astrology (Enneads II, 13) aroused wider controversy among savants. In it Plotinus argued that the relative positions of stars were not causes but signs of future events; this significance, which was in any case limited, depended on the mutual sympathy of the parts of the universe.

BIBLIOGRAPHY

The standard ed. is Plotini Opera, P. Henry and H. R. Schwyzer. eds. (Paris-Brussels, 1951–1973). English translations are by S. MacKenna, 3rd ed., rev. by B. S. Page (London, 1962), and, with Greek text, by A. H. Armstrong, in Loeb Classical Library (London–Cambridge, Mass., 1966– ); a German translation with explanatory notes is by R. Harder, R. Beutler, and W. Theiler (Hamburg, 1956–1967).

Secondary sources are Porphyry’s “Life of Plotinus,” included in all above eds.; Cambridge History of Later Greek and Early Medieval Philosophy, A. H. Armstrong, ed. (Cambridge, 1967), chs. 12–16; and A. C. Crombie, Robert Grosseteste and the Origins of Experimental Science 1100–1700 (Oxford, 1953), chs. 5,6.

A. C. Lloyd