The teachings of the Greek philosopher Plotinus, as written down by his student Porphyry. The word ennead means "set of nine" in Greek; Porphyry recorded 54 individual topics of Plotinus' philosophy and arranged them in these six volumes. These were published between 301 and 305 A.D. It is important to note that Porphyry refers to himself more as an editor than as an interpreter of his teacher's thought, as Plato was of Socrates, and therefore we can assume that the underlying text captures relatively faithfully the original teachings of Plotinus without significant emendation.