SOURCE: A preface to Plotinus, translated by A. H. Armstrong, Harvard University Press, 1966, pp. vii-xxxiii.

In the following excerpt, Armstrong summarizes Plotinus's system of thought and provides some background on the history of his writing.

I. the Enneads

Plotinus, as Porphyry tells us in his Life (ch. 4), did not begin to write till the first year of the reign of Gallienus (253/4), when he was forty-nine years old and had been settled at Rome and teaching philosophy for ten years. He continued to write till his death in 270 in his sixty-sixth year. His writings thus all belong to the last sixteen years of his life and represent his mature and fully developed thought. We should not expect to find in them, and, in the opinion at least of the great majority of Plotinian scholars, we do not in fact find in them, any major development. The earliest of them...