The Six Enneads is the collection of writings of Plotinus, edited and compiled by his student Porphyry. After correcting and naming each treatise, Porphyry wrote a biography of his master, Life of Plotinus, intended to be an Introduction to the Enneads. Porphyry's edition does not follow the chronological order in which Enneads were written, but responds to a plan of study which leads the learner from subjects related to his own affairs to subjects concerning the uttermost principles of the universe.